(meth)acrylate production system

ABSTRACT

A (meth)acrylate production system having a reactor (A 1 ) provided with a distillation column ( 2 ) and a distillation apparatus (B 3 ) provided with a distillation column ( 4 ). A condensing apparatus ( 6 ) is provided at the top of the distillation column ( 2 ). The condensing apparatus ( 6 ) and a switching apparatus ( 7 ) are connected via a pipe ( 5   b ), the switching apparatus ( 7 ) and the top of the distillation column ( 2 ) are connected via a pipe ( 5   c ), the switching apparatus ( 7 ) and a liquid separation apparatus ( 8 ) are connected via a pipe ( 5   d ), the top of the liquid separation apparatus ( 8 ) and the distillation column ( 2 ) are connected via pipe ( 5   e ), the bottom of the liquid separation apparatus ( 8 ) and the distillation apparatus (B 3 ) are connected via a pipe ( 50 , the top of the distillation column ( 4 ) is connected with a condensing apparatus ( 9 ) via a pipe ( 10   a ), the condensing apparatus ( 9 ) and a switching apparatus ( 11 ) are connected via a pipe ( 10   b ), the switching apparatus ( 11 ) and the top of the distillation column ( 4 ) are connected via a pipe ( 10   c ), the switching apparatus ( 11 ) and a recovery unit ( 12 ) are connected via a pipe ( 10   d ), and the bottom of the distillation apparatus (B 3 ) is connected with the pipe ( 5   d ) between the switching apparatus ( 7 ) and the liquid separation apparatus ( 8 ) via a pipe ( 10   e ).

TECHNICAL FIELD

The present invention relates to a system for producing a(meth)acrylate. More specifically, the present invention relates to asystem for producing a (meth)acrylate, which enables to efficientlyproduce a (meth)acrylate with transesterification. The (meth)acrylate isa useful compound, for example, as a raw material of a (meth)acrylicresin, a surfactant, an adhesive, a paint and the like, the kind ofwhich differs depending on the kind of the (meth)acrylate.

In this description, the term “(meth)acrylate” means “acrylate” and/or“methacrylate”.

BACKGROUND ART

As a method for efficiently separating methanol from a mixture of methyl(meth)acrylate and methanol by using a reactor having a distillationcolumn, there has been proposed a method which includes using anazeotropic solvent which forms an azeotropic mixture with methanol,refluxing a part of a condensate of a vapor, which is distilled out fromthe top of the distillation column, to the distillation column,separating the remaining condensate into two layers, supplying the upperlayer of the two layers to a middle stage of the distillation column,taking out the lower layer of the remaining condensate from thedistillation column, and collecting methyl (meth)acrylate from thebottom of the reactor (for example, see Patent Literature 1).

According to the above-mentioned method, methyl (meth)acrylate can becollected from the bottom of the reactor. However, after the collectionof the methyl (meth)acrylate, methyl (meth)acrylate remaining in thereactor cannot be collected.

As a method for producing a (meth)acrylate as an objective compound byusing a transesterification reaction of an alkyl (meth)acrylate used asa raw material and an alcohol, there has been proposed a method forproducing a (meth)acrylate which includes, in carrying out atransesterification reaction in the presence of an azeotropic solventwhich forms an azeotropic mixture with an alkyl alcohol which isgenerated as a by-product, removing the alkyl alcohol generated as aby-product together with the azeotropic solvent from a distillationoutlet provided at the upper part of the distillation column,controlling the temperature of vapor distilled out from the distillationoutlet to a temperature not lower than the azeotropic temperature of thealkyl alcohol which is generated as a by-product and the azeotropicsolvent, and a temperature not higher than a temperature 2° C. higherthan the azeotropic temperature, and controlling the temperature at thebottom of the distillation column to a temperature not lower than atemperature 10° C. lower than the boiling point of the azeotropicsolvent, and a temperature not higher than the boiling point of theazeotropic solvent (for example, see Patent Literature 2).

According to the above-mentioned method for producing a (meth)acrylate,it has been considered that a Michael addition reaction which is a sidereaction can be inhibited, and that a (meth)acrylate can be produced inhigh productivity. However, an alkyl (meth)acrylate used as a rawmaterial remains in the reaction system after an objective(meth)acrylate is produced, and there has not yet been considered asystem which enables to efficiently collect the remaining alkyl(meth)acrylate used as a raw material in the reaction system.

Therefore, it has been desired to develop a system for producing a(meth)acrylate with transesterification, which enables to efficientlycollect and reuse a (meth)acrylate which is used as a raw material, asolvent, an alcohol generated as a by-product and the like, remaining ina reaction system after an objective (meth)acrylate is produced bytransesterification, and which enables to efficiently produce anobjective (meth)acrylate.

PRIOR ART LITERATURES Patent Literatures

-   Patent Literature 1: Japanese Unexamined Patent Publication No. Hei    8-268938-   Patent Literature 2: Japanese Unexamined Patent Publication No.    2004-189650

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The present invention has been achieved in view of the above-mentionedprior arts. An object of the present invention is to provide a systemfor producing a (meth)acrylate by means of transesterification, whichenables to efficiently collect and reuse a (meth)acrylate which is usedas a raw material, a solvent, an alcohol generated as a by-product andthe like, remaining in a reaction system after an objective(meth)acrylate is produced by transesterification, and which enables toefficiently produce an objective (meth)acrylate.

Means for Solving the Problems

The present invention relates to

(1) a system (an apparatus) for producing a (meth)acrylate used inproducing a (meth)acrylate by transesterification, which includes areactor A having a distillation column and a distillation apparatus Bhaving a distillation column, wherein

an upper part of the distillation column of the reactor A is connectedwith a condensing apparatus through a pipe; the condensing apparatus isconnected with the upper part of the distillation column through aswitching apparatus with a pipe for refluxing a part of a condensateobtained in the condensing apparatus to the upper part of thedistillation column; and the condensing apparatus is connected with aliquid separation apparatus through the switching apparatus with a pipefor feeding the condensate remaining in the condensing apparatus to theliquid separation apparatus;

an upper part of the liquid separation apparatus is connected with thedistillation column through a pipe for refluxing an upper layer of thecondensate separated by the liquid separation apparatus to thedistillation column; and a lower part of the liquid separation apparatusis connected with the distillation apparatus B through a pipe forfeeding a lower layer of the condensate separated by the liquidseparation apparatus to the distillation apparatus B;

an upper part of the distillation column of the distillation apparatus Bis connected with a condensing apparatus through a pipe; the condensingapparatus is connected with the upper part of the distillation columnthrough a switching apparatus with a pipe for refluxing a part of acondensate obtained in the condensing apparatus to the upper part of thedistillation column; and the condensing apparatus is connected with acollecting unit for collecting the condensate remaining in thecondensing apparatus through a switching apparatus with a pipe forfeeding the remaining condensate to the collecting unit; and

a lower part of the distillation apparatus B is connected with a pipebetween the switching apparatus and the condensing apparatus in thereactor A through a pipe for refluxing a residue existing in thedistillation apparatus B to the distillation column of the reactor A;and

(2) a system (an apparatus) for producing a (meth)acrylate used inproducing a (meth)acrylate by transesterification, which includes areactor A having a distillation column, a distillation apparatus Bhaving a distillation column, and a distillation apparatus C having adistillation column, wherein

an upper part of the distillation column of the reactor A is connectedwith a condensing apparatus through a pipe; the condensing apparatus isconnected with the upper part of the distillation column through aswitching apparatus with a pipe for refluxing a part of a condensateobtained in the condensing apparatus to the upper part of thedistillation column; and the condensing apparatus is connected with aliquid separation apparatus through a switching apparatus with a pipefor feeding the condensate remaining in the condensing apparatus to theliquid separation apparatus;

an upper part of the liquid separation apparatus is connected with thedistillation column through a pipe for refluxing an upper layer of thecondensate separated by the liquid separation apparatus to thedistillation column; and a lower part of the liquid separation apparatusis connected with the distillation apparatus B through a pipe forfeeding a lower layer of the condensate separated by the liquidseparation apparatus to the distillation apparatus B;

an upper part of the distillation column of the distillation apparatus Bis connected with a condensing apparatus through a pipe; the condensingapparatus is connected with the upper part of the distillation columnthrough a switching apparatus with a pipe for refluxing a part of acondensate obtained in the condensing apparatus to the upper part of thedistillation column; and the condensing apparatus is connected with acollecting unit for collecting the condensate remaining in thecondensing apparatus through a switching apparatus with a pipe forfeeding the remaining condensate to the collecting unit;

a lower part of the distillation apparatus B is connected with thedistillation apparatus C through a pipe for feeding a residue existingin the distillation apparatus B to the distillation column of thedistillation apparatus C;

an upper part of the distillation apparatus C is connected with acondensing apparatus through a pipe; the condensing apparatus isconnected with the upper part of the distillation column through aswitching apparatus with a pipe for refluxing a part of a condensateobtained in the condensing apparatus to the upper part of thedistillation column; and the condensing apparatus is connected with acollecting unit for collecting the condensate remaining in thecondensing apparatus through a pipe for feeding the condensate remainingin the condensing apparatus to the collecting unit; and

a lower part of the distillation apparatus C is connected with a pipebetween the switching apparatus and the condensing apparatus in thereactor A through a pipe for feeding a residue existing in thedistillation apparatus C to the distillation column of the reactor A.

Effects of the Invention

According to the system for producing a (meth)acrylate of the presentinvention, there are exhibited excellent effects such that a(meth)acrylate which is used as a raw material, a solvent, an alcoholwhich is generated as a by-product and the like, remaining in a reactionsystem after producing an objective (meth)acrylate bytransesterification can be efficiently collected and reused, and anobjective (meth)acrylate can be efficiently produced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic drawing showing one embodiment of a system forproducing a (meth)acrylate according to the present invention.

FIG. 2 is a schematic drawing showing another embodiment of a system forproducing a (meth)acrylate according to the present invention.

MODES FOR CARRYING OUT THE INVENTION

Generally, a (meth)acrylate such as methyl (meth)acrylate is sensitiveto a temperature, and easily polymerizes. Therefore, in order to inhibitthe polymerization of the (meth)acrylate, it can be considered to use asystem for collecting a (meth)acrylate which is used as a raw materialremaining in a reactor by reduced-pressure distillation at a lowtemperature.

However, when the (meth)acrylate is collected by reduced-pressuredistillation at a low temperature, in the case where the boiling pointof the (meth)acrylate is low, and the vapor pressure of the(meth)acrylate is high, it is difficult to trap the vapor of the(meth)acrylate with a condensing apparatus, and the vapor is scatteredto the air. Therefore, the (meth)acrylate cannot be efficientlycollected, and there is a possibility that an offensive odor of the(meth)acrylate is diffused to the air.

In order to avoid the diffusion of the vapor of the (meth)acrylate tothe air, it can be considered to use an apparatus for treating exhaustgas in the condensing apparatus. However, when the apparatus fortreating exhaust gas is used, there arise some secondary problems suchas treatment of waste liquid which is generated from the apparatus fortreating exhaust gas, and increase in costs such as equipment costs foruse of an apparatus for treating exhaust gas and maintenance costs ofthe apparatus for treating exhaust gas.

Therefore, the present inventors have earnestly studied to overcome theabove problems. As a result, when a system for producing a(meth)acrylate which is functionally constructed by using a reactor Ahaving a distillation column and a distillation apparatus B having adistillation column, or a system for producing a (meth)acrylate which isfunctionally constructed by using a reactor A having a distillationcolumn, a distillation apparatus B having a distillation column and adistillation apparatus C having a distillation column, a (meth)acrylatewhich is used as a raw material remaining in the reactor A can beefficiently collected from the reactor A under atmospheric pressurewithout an operation for reduced pressure as mentioned above; a solvent,an alcohol generated as a by-product and the like can be efficientlycollected and reused; and an objective (meth)acrylate can be efficientlyproduced. Furthermore, it has also been found out that the collected(meth)acrylate used as a raw material can be suitably used as a rawmaterial when a new transesterification reaction of a material(meth)acrylate and an alcohol corresponding to an objective(meth)acrylate is carried out.

Thus, according to the system for producing a (meth)acrylate of thepresent invention, there is no necessity to use an operation forreducing a pressure; a (meth)acrylate used as a raw material remainingin a reactor A can be efficiently collected under atmospheric pressure;a solvent, an alcohol generated as a by-product and the like can beefficiently collected and reused; an objective (meth)acrylate can beefficiently produced; and moreover the collected (meth)acrylate can bereused.

Therefore, the system for producing a (meth)acrylate of the presentinvention is a system for producing a (meth)acrylate in high industrialproductivity.

As described above, the system for producing a (meth)acrylate of thepresent invention is a system for producing a (meth)acrylate when a(meth)acrylate is produced by transesterification.

The system for producing a (meth)acrylate of the present invention has areactor A having a distillation column and a distillation apparatus Bhaving a distillation column. An upper part of the distillation columnof the reactor A is connected with a condensing apparatus through apipe, the condensing apparatus is connected with the upper part of thedistillation column through a switching apparatus with a pipe forrefluxing a part of a condensate obtained in the condensing apparatus tothe upper part of the distillation column, and the condensing apparatusis connected with a liquid separation apparatus through the switchingapparatus with a pipe for feeding the condensate remaining in thecondensing apparatus to the liquid separation apparatus; an upper partof the liquid separation apparatus is connected with the distillationcolumn through a pipe for refluxing an upper layer of the condensateseparated by the liquid separation apparatus to the distillation column,and a lower part of the liquid separation apparatus is connected withthe distillation apparatus B through a pipe for feeding a lower layer ofthe condensate separated by the liquid separation apparatus to thedistillation apparatus B; an upper part of the distillation column ofthe distillation apparatus B is connected with a condensing apparatusthrough a pipe, the condensing apparatus is connected with the upperpart of the distillation column through a switching apparatus with apipe for refluxing a part of a condensate obtained in the condensingapparatus to the upper part of the distillation column, and thecondensing apparatus is connected with a collecting unit for collectingthe condensate remaining in the condensing apparatus through a switchingapparatus with a pipe for feeding the remaining condensate to thecollecting unit; and a lower part of the distillation apparatus B isconnected with a pipe between the switching apparatus and the condensingapparatus in the reactor A through a pipe for refluxing a residueexisting in the distillation apparatus B to the distillation column ofthe reactor A.

In addition, the system for producing a (meth)acrylate of anotherembodiment of the present invention has a reactor A having adistillation column, a distillation apparatus B having a distillationcolumn and a distillation apparatus C having a distillation column. Anupper part of the distillation column of the reactor A is connected witha condensing apparatus through a pipe, the condensing apparatus isconnected with the upper part of the distillation column through aswitching apparatus with a pipe for refluxing a part of a condensateobtained in the condensing apparatus to the upper part of thedistillation column, and the condensing apparatus is connected with aliquid separation apparatus through a switching apparatus with a pipefor feeding the condensate remaining in the condensing apparatus to theliquid separation apparatus; an upper part of the liquid separationapparatus is connected with the distillation column through a pipe forrefluxing an upper layer of the condensate separated by the liquidseparation apparatus to the distillation column, and a lower part of theliquid separation apparatus is connected with the distillation apparatusB through a pipe for feeding a lower layer of the condensate separatedby the liquid separation apparatus to the distillation apparatus B; anupper part of the distillation column of the distillation apparatus B isconnected with a condensing apparatus through a pipe, the condensingapparatus is connected with the upper part of the distillation columnthrough a switching apparatus with a pipe for refluxing a part of acondensate obtained in the condensing apparatus to the upper part of thedistillation column, and the condensing apparatus is connected with acollecting unit for collecting the condensate remaining in thecondensing apparatus through a switching apparatus with a pipe forfeeding the remaining condensate to the collecting unit; a lower part ofthe distillation apparatus B is connected with the distillationapparatus C through a pipe for feeding a residue existing in thedistillation apparatus B to the distillation column of the distillationapparatus C; an upper part of the distillation apparatus C is connectedwith a condensing apparatus through a pipe; the condensing apparatus isconnected with the upper part of the distillation column through aswitching apparatus with a pipe for refluxing a part of a condensateobtained in the condensing apparatus to the upper part of thedistillation column, and the condensing apparatus is connected with acollecting unit for collecting the condensate remaining in thecondensing apparatus through a pipe for feeding the condensate remainingin the condensing apparatus to the collecting unit; and a lower part ofthe distillation apparatus C is connected with a pipe between theswitching apparatus and the condensing apparatus in the reactor Athrough a pipe for feeding a residue existing in the distillationapparatus C to the distillation column of the reactor A.

In the system for producing a (meth)acrylate of the present invention, a(meth)acrylate which is used as a raw material includes, for example, analkyl (meth)acrylate having an alkyl group of 1 to 8 carbon atoms, suchas methyl (meth)acrylate, and the like, and the present invention is notlimited only to those exemplified ones.

A transesterification of the (meth)acrylate which used as a raw materialand an alcohol corresponding to an objective (meth)acrylate can becarried out by any one of a flow method and a batch method.

In the present invention, first of all, a transesterification of the(meth)acrylate which used as a raw material and an alcohol correspondingto an objective (meth)acrylate is carried out.

The alcohol which is used as a raw material in carrying out atransesterification of the (meth)acrylate is appropriately selected inaccordance with an objective (meth)acrylate. More specifically, as theabove-mentioned alcohol, an alcohol which forms an ester group of anobjective (meth)acrylate is used. As one example, when an objective(meth)acrylate is, for example, n-propyl (meth)acrylate, n-propylalcohol is used as an alcohol which forms the propyl group.

The alcohol corresponding to an objective (meth)acrylate includes, forexample, an aliphatic or alicyclic alcohol represented by the formula(I);

[Chem. 1]

R¹OH  (1)

wherein R¹ is an alkyl group having 2 to 30 carbon atoms which may havea cyclic structure, such as ethyl alcohol, n-propyl alcohol, isopropylalcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol,tert-butyl alcohol, n-pentyl alcohol, n-hexyl alcohol, isohexyl alcohol,cyclohexyl alcohol, 3,3,5-trimethylcyclohexyl alcohol,4-tert-butylcyclohexyl alcohol, n-heptyl alcohol, n-octyl alcohol,isooctyl alcohol, 2-ethylhexyl alcohol, 3,4-dimethylhexyl alcohol,3,4-dimethylheptyl alcohol, lauryl alcohol, nonyl alcohol, isononylalcohol, stearyl alcohol or 2-heptylundecan-1-ol; an aromatic alcoholsuch as phenol, benzyl alcohol, 1-phenylethyl alcohol, 2-phenylethylalcohol or phenoxyethanol; an amino alcohol represented by the formula(II);

wherein each of R² and R³ is independently hydrogen atom or an alkylgroup having 1 to 8 carbon atoms, and R⁴ is an alkylene group having 1to 4 carbon atoms, such as dimethylaminoethyl alcohol, diethylaminoethylalcohol, dipropylaminoethyl alcohol, dibutylaminoethyl alcohol,dipentylaminoethyl alcohol, dihexylaminoethyl alcohol, dioctylaminoethylalcohol, methylethylaminoethyl alcohol, methylpropylaminoethyl alcohol,methylbutylaminoethyl alcohol, methylhexylaminoethyl alcohol,ethylpropylaminoethyl alcohol, ethylbutylaminoethyl alcohol,ethylpentylaminoethyl alcohol, ethyloctylaminoethyl alcohol,propylbutylaminoethyl alcohol, dimethylaminopropyl alcohol,diethylaminopropyl alcohol, dipropylaminopropyl alcohol,dibutylaminopropyl alcohol or butylpentylaminopropyl alcohol; an alkoxyalcohol such as 2-methoxyethyl alcohol, ethoxyethyl alcohol, butoxyethylalcohol, ethylene glycol monomethyl ether, ethylene glycol monoethylether (ethyl carbitol), triethylene glycol monomethyl ether,tetrahydrofurfuryl alcohol, 2-ethyl-2-methyl-1,3-dioxolane-4-methylalcohol, cyclohexanespiro-2-1,3-dioxolane-4-methyl alcohol,3-ethyl-3-oxetanylmethyl alcohol, or 3-ethyl-3-oxetanylmethyl alcohol; amonohydric alcohol such as allyl alcohol, methallyl alcohol ortetrahydrofurfuryl alcohol; a dihydric alcohol such as ethylene glycol,2,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol,trimethylolpropane or cyclohexanediol; and a polyhydric alcohol havingat least three hydroxyl groups such as glycerol, and the like, and thepresent invention is not limited only to those exemplified ones. Thesealcohols can be used alone, or at least two kinds thereof can be used incombination.

The amount of the (meth)acrylate which is used as a raw material ispreferably 0.3 equivalent or more, more preferably 0.5 equivalent ormore and furthermore preferably 0.8 equivalent or more per oneequivalent of hydroxyl group of an alcohol corresponding to an objective(meth)acrylate from the viewpoint of increase in reaction rate oftransesterification of the (meth)acrylate which is used as a rawmaterial and the alcohol, and is preferably 5 equivalents or less, morepreferably 4 equivalents or less and furthermore preferably 3equivalents or less per one equivalent of hydroxyl group of the alcoholcorresponding to an objective (meth)acrylate from the viewpoint ofreduction of the amount of unreacted (meth)acrylate which is used as araw material.

A preferred (meth)acrylate which is used as a raw material includesmethyl (meth)acrylate.

When the transesterification of the (meth)acrylate which is used as araw material and an alcohol corresponding to an objective (meth)acrylateis carried out, a transesterification catalyst can be used.

The transesterification catalyst includes, for example, hydroxides suchas lithium hydroxide, sodium hydroxide, potassium hydroxide, cesiumhydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide andstrontium hydroxide; hydrogen carbonates such as lithium hydrogencarbonate, sodium hydrogen carbonate, potassium hydrogen carbonate,cesium hydrogen carbonate, magnesium hydrogen carbonate, calciumhydrogen carbonate, barium hydrogen carbonate and strontium hydrogencarbonate; carbonates such as lithium carbonate, sodium carbonate,potassium carbonate, cesium carbonate, magnesium carbonate, calciumcarbonate, barium carbonate and strontium carbonate; acetates such aslithium acetate, sodium acetate, potassium acetate, cesium acetate,magnesium acetate, calcium acetate, barium acetate and strontiumacetate; borohydrides such as lithium borohydride, sodium borohydride,potassium borohydride and cesium borohydride; salts of stearic acid suchas lithium stearate, sodium stearate, potassium stearate, cesiumstearate, magnesium stearate, calcium stearate, barium stearate andstrontium stearate; phenylborates such as lithium phenylborate, sodiumphenylborate, potassium phenylborate and cesium phenylborate; benzoatessuch as lithium benzoate, sodium benzoate, potassium benzoate and cesiumbenzoate; hydrogenphosphates such as dilithium hydrogenphosphate,disodium hydrogenphosphate, dipotassium hydrogenphosphate and dicesiumhydrogenphosphate; phenylphosphates such as dilithium phenylphosphate,disodium phenylphosphate, dipotassium phenylphosphate and dicesiumphenylphosphate; metal alkoxides such as sodium alkoxide and titaniumalkoxide; tetraalkoxytitaniums such as tetramethoxytitanium,tetraethoxytitanium, tetrapropoxytitanium and tetrabutoxytitanium;dialkyltin oxides such as dialkyltin oxides having an alkyl group of 4to 18 carbon atoms, such as dibutyltin oxide, dioctyltin oxide anddilauryltin oxide; metal alcoholates such as titanium alcoholate,aluminum alcoholate and magnesium alcoholate, and the like, and thepresent invention is not limited only to those exemplified ones. Thesetransesterification catalysts can be used alone, or at least two kindsthereof can be used in combination. Among these transesterificationcatalysts, a tetraalkoxytitanium and a dialkyltin oxide having an alkylgroup of 4 to 12 carbon atoms are preferable, a tetraalkoxytitanium anda dialkyltin oxide having an alkyl group of 4 to 8 carbon atoms are morepreferable, and tetramethoxytitanium, dibutyltin oxide and dioctyltinoxide are furthermore preferable, from the viewpoint of acceleration oftransesterification.

The amount of the transesterification catalyst cannot be absolutelydetermined since the amount differs depending on the kind of thetransesterification catalyst. Therefore, it is preferred that the amountof the transesterification catalyst is appropriately determined inaccordance with the kind of the transesterification catalyst. The amountof the transesterification catalyst is usually preferably 0.00001 molesor more, more preferably 0.0001 moles or more per one mole of the(meth)acrylate which is used as a raw material, from the viewpoint ofefficient progress of transesterification of the (meth)acrylate which isused as a raw material and the alcohol, and is preferably 0.10 moles orless, more preferably 0.05 moles or less per one mole of the(meth)acrylate which is used as a raw material, from the viewpoint ofimprovement in economic efficiency.

When the transesterification reaction of the (meth)acrylate which isused as a raw material and an alcohol corresponding to an objective(meth)acrylate is carried out, a polymerization inhibitor also can beused. The polymerization inhibitor includes, for example, N-oxyradicalcompounds such as

4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl,4-acetoamino-2,2,6,6-tetramethylpiperidine-N-oxyl,4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl,4-oxo-2,2,6,6-tetramethylpiperidine-N-oxyl and2,2,6,6-tetramethylpiperidine-N-oxyl; phenol compounds such asparamethoxyphenol, 2,2′-methylenebis(4-ethyl-6-tert-butylphenol),2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-N,N-dimethylamino-p-cresol, 2,4-dimethyl-6-tert-butylphenol,4-tert-butylcatechol, 4,4′-thio-bis(3-methyl-6-tert-butylphenol) and4,4′-butylidene-bis(3-methyl-6-tert-butylphenol); quinone compounds suchas methoquinone, hydroquinone, 2,5-di-tert-butylhydroquinone,2,6-di-tert-butylhydroquinone and benzoquinone; copperdialkyldithiocarbamate such as cuprous chloride and copperdimethyldithiocarbamate; amino compounds such as phenothiazine,N,N′-diphenyl-p-phenylenediamine, phenyl-β-naphthylamine,N,N′-di-β-naphthyl-p-phenylenediamine andN-phenyl-N′-isopropyl-p-phenylenediamine; hydroxyamine compounds such as1,4-dihydroxy-2,2,6,6-tetramethylpiperidine,1-hydroxy-2,2,6,6-tetramethylpiperidine and4-hydroxy-2,2,6,6-tetramethylpiperidine, and the like, and the presentinvention is not limited only to those exemplified ones. Thesepolymerization inhibitors can be used alone, or at least two kindsthereof can be used in combination.

The amount of the polymerization inhibitor is preferably 0.00001 partsby mass or more, more preferably 0.00005 parts by mass or more,furthermore preferably 0.0001 parts by mass or more per 100 parts bymass of the (meth)acrylate which is used as a raw material, from theviewpoint of inhibition of polymerization of the (meth)acrylate which isused as a raw material and an objective (meth)acrylate, and ispreferably 0.1 parts by mass or less, more preferably 0.05 parts by massor less, furthermore preferably 0.01 parts by mass or less per 100 partsby mass of the (meth)acrylate which is used as a raw material, from theviewpoint of increase in purity of an objective (meth)acrylate.

When the transesterification reaction of the (meth)acrylate which isused as a raw material and the alcohol corresponding to an objective(meth)acrylate is carried out in the reactor A, it is preferred as asolvent to use an azeotropic solvent which forms an azeotropic mixturetogether with an alcohol which is generated as a by-product (hereafterreferred to as by-product alcohol) by transesterification of the(meth)acrylate which is used as a raw material and the alcoholcorresponding to an objective (meth)acrylate at a temperature equal toor lower than the boiling point of the by-product alcohol, and whichforms an azeotropic mixture together with the (meth)acrylate which isused as a raw material at a temperature equal to or lower than theboiling point of the (meth)acrylate which is used as a raw material.

When the azeotropic solvent which forms an azeotropic mixture togetherwith the by-product alcohol at a temperature equal to or lower than theboiling point of the by-product alcohol, and which forms an azeotropicmixture together with the (meth)acrylate which is used as a raw materialat a temperature equal to or lower than the boiling point of the(meth)acrylate which is used as a raw material is used as a solvent,after the transesterification reaction of the (meth)acrylate which isused as a raw material and the alcohol corresponding to an objective(meth)acrylate is carried out, the (meth)acrylate which is used as a rawmaterial existing in the reactor A can be efficiently collected from thereactor A.

When the (meth)acrylate which is used as a raw material is, for example,methyl (meth)acrylate, the by-product alcohol is methanol. In this case,as the azeotropic solvent which forms an azeotropic mixture togetherwith the by-product alcohol at a temperature equal to or lower than theboiling point of the by-product alcohol, and which forms an azeotropicmixture together with the (meth)acrylate which is used as a raw materialat a temperature equal to or lower than the boiling point of the(meth)acrylate which is used as a raw material, there can be exemplifiedcyclohexane, n-hexane and the like, and the present invention is notlimited only to those exemplified ones. These azeotropic solvents can beused alone, or at least two kinds thereof can be used in combination.Among these azeotropic solvents, cyclohexane is preferable from theviewpoint of shortening of a period of time necessary fortransesterification, and efficient collection of the (meth)acrylatewhich is used as a raw material.

The amount of the solvent is not particularly limited, and can beusually 5 to 200 parts by mass or so per 100 parts by mass of the sum ofthe (meth)acrylate which is used as a raw material and the alcoholcorresponding to an objective (meth)acrylate.

Incidentally, within a scope which would not hinder an object of thepresent invention, other solvent can be used. The other solventincludes, for example, aliphatic hydrocarbon compounds having 5 to 8carbon atoms other than cyclohexane, such as n-pentane, n-hexane,isohexane, n-heptane, n-octane, 2,3-dimethybutane, 2,5-dimethylhexaneand 2,2,4-trimethylpentane, and the like, and the present invention isnot limited only to those exemplified ones.

Next, the system for producing a (meth)acrylate of the present inventionwill be more specially described based on drawings. However, the presentinvention is not limited only to the embodiments shown in the drawings.

FIG. 1 is a schematic drawing which shows one embodiment of a system forproducing a (meth)acrylate according to the present invention.

The system for producing a (meth)acrylate shown in FIG. 1 has a reactorA1 having a distillation column 2 and a distillation apparatus B3 havinga distillation column 4.

In the present invention, the reactor A1 having the distillation column2 is used when the transesterification of the (meth)acrylate used as araw material and the alcohol corresponding to an objective(meth)acrylate is carried out.

The reactor A1 having the distillation column 2 includes, for example, areactor having a distillation column such as a rectification column, afluidized bed, a fixed bed or a reaction distillation column, and thelike, and the present invention is not limited only to those exemplifiedones. In addition, the structure and type of the distillation column 2are not particularly limited. Among distillation columns 2, adistillation column having a high efficiency for gas-liquid contact ispreferable. A suitable distillation column 2 includes, for example, apacked column type distillation column, a tray type distillation columnand the like. The tray type distillation column includes, for example, apacked distillation column, an Oldershaw type distillation column, alift-tray type distillation column and the like, and the presentinvention is not limited only to those exemplified ones. The number oftheoretical stages of the distillation column 2 is preferably 7 or more,more preferably 10 or more, furthermore preferably 15 or more, from theviewpoint of efficient and stable progress of the transesterification ofthe (meth)acrylate used as a raw material and the alcohol correspondingto an objective (meth)acrylate, and is preferably 100 or less, morepreferably 70 or less, furthermore preferably 50 or less, from theviewpoint of improvement in economic efficiency.

A condensing apparatus 6 is connected with the distillation column 2 ofthe reactor A1 at an upper part of the distillation column 2, preferablyat the top of the distillation column 2 through a pipe 5 a. In addition,in order to reflux a part of a condensate obtained in the condensingapparatus 6 to an upper part of the distillation column 2, preferablythe top of the distillation column 2, the condensing apparatus 6 isconnected with a switching apparatus 7 through a pipe 5 b, and theswitching apparatus 7 is connected with the distillation column 2 at anupper part of the distillation column 2, preferably the top of thedistillation column 2 through a pipe 5 c. The condensing apparatus 6includes, for example, a condenser and the like, and the presentinvention is not limited only to the exemplified one. The switchingapparatus 7 is used in order to feed the condensate obtained in thecondensing apparatus 6 to the upper part, preferably the top of thedistillation column 2 or a liquid separation apparatus 8. The switchingapparatus 7 includes, for example, a switching valve, a refluxdistributor, a solenoid valve and the like, and the present invention isnot limited only to those exemplified ones.

In order to feed the condensate remaining in the condensing apparatus 6to the liquid separation apparatus 8, the condensing apparatus 6 isconnected with the switching apparatus 7 through the pipe 5 b, and theswitching apparatus 7 is connected with the liquid separation apparatus8 through a pipe 5 d. Therefore, a part of the condensate obtained inthe condensing apparatus 6 is fed to the upper part, preferably the topof the distillation column 2 through the switching apparatus 7, and theremaining condensate is fed to the liquid separation apparatus 8 byswitching of the switching apparatus 7. The liquid separation apparatus8 is used when the condensate is separated into two layers of an upperlayer and a lower layer. The liquid separation apparatus 8 includes, forexample, a decanter, a separating funnel and an oil-water separatingapparatus and the like, and the present invention is not limited only tothose exemplified ones.

The upper part of the liquid separation apparatus 8 is connected withthe distillation column 2 through a pipe 5 e in order to reflux theupper layer of the condensate separated by the liquid separationapparatus 8 to the distillation column 2. The position where the pipe 5e is connected with the distillation column 2 is not particularlylimited, and it is preferred that the pipe 5 e is connected with thedistillation column 2 at a middle stage from the viewpoint of anefficient transesterification reaction of the (meth)acrylate which isused as a raw material and an alcohol corresponding to an objective(meth)acrylate. The middle stage of the distillation column 2 means acentral position of a multistage distillation column. When thedistillation column 2 is, for example, a distillation column having anumber of theoretical stages of 15, 6 to 9 stages of the distillationcolumn correspond to the middle stage of the distillation column 2.

The lower part of the liquid separation apparatus 8 is connected withthe distillation apparatus B3 through a pipe 5 f in order to feed thelower layer of the condensate separated by the liquid separationapparatus 8 to the distillation apparatus B3.

The distillation apparatus B3 having the distillation column 4 can beany one of a batch type distillation apparatus and a flow typedistillation apparatus. The distillation column 4 of the distillationapparatus B3 includes, for example, a packed column, a tray typedistillation column and the like, and the present invention is notlimited only to those exemplified ones. A filler used in the packedcolumn includes, for example, Helipack, McMahon, Cascade Mini Ring andthe like, and the present invention is not limited only to thoseexemplified ones. The tray type distillation column includes, forexample, a packed distillation column, an Oldershaw distilling column, aLift Tray distillation column and the like, and the present invention isnot limited only to those exemplified ones.

The upper part, preferably the top of the distillation column 4 of thedistillation apparatus B3 is connected with a condensing apparatus 9through a pipe 10 a. In order to reflux a part of the condensateobtained in the condensing apparatus 9 to the upper part, preferably thetop of the distillation column 4, the condensing apparatus 9 isconnected with a switching apparatus 11 through a pipe 10 b, and theswitching apparatus 11 is connected with the upper part, preferably thetop of the distillation column 4 through a pipe 10 c.

In order to collect the condensate remaining in the condensing apparatus9, the condensing apparatus 9 is connected with the switching apparatus11 through the pipe 10 b, and the switching apparatus 11 is connectedwith a collecting unit 12 through a pipe 10 d. Therefore, a part of thecondensate obtained in the condensing apparatus 9 is fed to the upperpart, preferably the top of the distillation column 4, and the remainingcondensate is fed to the collecting unit 12 by switching the switchingapparatus 11. The switching apparatus 11 includes, for example, aswitching valve, a reflux distributor, a solenoid valve and the like,and the present invention is not limited only to those exemplified ones.In addition, the collecting unit 12 can be a so-called receiver.

A pipe 10 e is connected with the lower part of the distillationapparatus B3 in order to reflux a residue existing in the distillationapparatus B3 to the distillation column 2 of the reactor A1. The otherend of the pipe 10 e is connected with the pipe 5 d positioning betweenthe switching apparatus 7 of the reactor A1 and the liquid separationapparatus 8 through, for example, a three-way cock (not illustrated inthe figure) or the like.

It is preferred that vapor of a by-product alcohol is removed from theupper part, preferably the top of the distillation column 2 of thereactor A1 by carrying out the azeotrope of a solvent and the by-productalcohol from the viewpoint of an efficient transesterification reactionof the (meth)acrylate which is used as a raw material and an alcoholcorresponding to an objective (meth)acrylate. It is preferred that thetemperature at the top of the distillation column 2 is controlled so asto be within a temperature range from the azeotropic temperature of theby-product alcohol and the solvent to a temperature which is 5° C.higher than the azeotropic temperature, preferably a temperature whichis 2° C. higher than the azeotropic temperature, from the viewpoint ofefficient removal of the solvent and the by-product alcohol from thereactor A1.

The by-product alcohol can be collected as a condensate by taking outvapor from the upper part of the distillation column 2, and condensingthe vapor by means of the condensing apparatus 6 while thetransesterification reaction of the (meth)acrylate which is used as araw material and an alcohol corresponding to an objective (meth)acrylateis carried out. A part of the condensate obtained in the condensingapparatus 6 is refluxed to the distillation column 2 by operating theswitching apparatus 7 so as to connect the pipe 5 b with the pipe 5 c.The remaining condensate is removed from the reactor A1 through theliquid separation apparatus 8 by operating the switching apparatus 7 soas to connect the pipe 5 b with the pipe 5 d. The temperature of theupper part of the distillation column 2 can be easily controlled to anazeotropic temperature of the by-product alcohol and the solvent byoperating the switching apparatus 7 so as to reflux the condensateobtained in the condensing apparatus 6 to the distillation column 2 orto remove the condensate to the outside of the reactor A1 without thecontrol of the heating temperature of the reactor A1.

The condensate which is removed from the reactor A1 by operating theswitching apparatus 7 so as to connect the pipe 5 b with the pipe 5 d isfed to the liquid separation apparatus 8. The condensate can beefficiently separated into two layers of an upper layer and a lowerlayer by adding water to the condensate which is fed to the liquidseparation apparatus 8. The amount of the water per 100 parts by volumeof the condensate is not particularly limited, and is usually preferably10 parts by volume or more, more preferably 20 parts by volume or more,from the viewpoint of efficient separation of the upper layer from thelower layer, and is preferably 300 parts by volume or less, morepreferably 200 parts by volume or less, from the viewpoint of reductionof the amount of the resulting lower layer.

Incidentally, when water is added to the condensate, the temperature ofthe condensate is preferably 0° C. to 50° C., more preferably 0° C. to40° C., and furthermore preferably 0° C. to 30° C., from the viewpointof efficient separation of the condensate into two layers of an upperlayer and a lower layer.

The upper layer of the separated two layers mainly contains a solvent.The solvent contained in this upper layer can be effectively used as asolvent when a transesterification reaction of the (meth)acrylate whichis used as a raw material and the alcohol corresponding to an objective(meth)acrylate is carried out.

Therefore, it is preferred that the above-mentioned upper layer isrefluxed to the distillation column 2 in the present invention from theviewpoint of effective use of the solvent contained in the upper layer.When the above-mentioned upper layer is supplied to the distillationcolumn 2, it is preferred that the upper layer is supplied to a middlestage of the distillation column 2 from the viewpoint of efficientprogress of the transesterification reaction of the (meth)acrylate whichis used as a raw material and the alcohol. Incidentally, the middlestage of the distillation column 2 means a central stage of a multistagedistillation column as described above. When the distillation column 2is, for example, a distillation column having a number of theoreticalstages of 15, 6 to 9 stages of the distillation column correspond to themiddle stage of the distillation column.

In addition, the fractionating capacity of the distillation column 2 canbe enhanced by refluxing a part of the condensate to the upper part,preferably the top of the distillation column 2 through the pipe 5 d,the switching apparatus 7 and the pipe 5 c. The amount of the condensatewhich is refluxed to the upper part of the distillation column 2 is notparticularly limited, and is preferably 20 to 95% by mass or so, morepreferably 50 to 90% by mass or so of the total amount of the condensatefrom the viewpoint of enhancement in fractionating capacity of thedistillation column 2 and increase in reaction rate.

After a part of the condensate of vapor which is taken out from theupper part of the distillation column 2 is refluxed to the upper part ofthe distillation column 2, it is preferred that water is added to theremaining condensate in the same manner as described above, to separateinto two layers of an upper layer and a lower layer. The upper layer ofthe separated two layers mainly contains a solvent. Therefore, the upperlayer can be effectively used as a reaction solvent which is used in thetransesterification reaction of the (meth)acrylate which is used as araw material and the alcohol corresponding to an objective(meth)acrylate in the same manner as described above. At that time, itis preferred that the above-mentioned upper layer is supplied to amiddle stage of the distillation column 2 in the same manner asdescribed above from the viewpoint of efficient progress of thetransesterification reaction of the (meth)acrylate which is used as araw material and the alcohol.

On the other hand, the above-mentioned lower layer mainly contains aby-product alcohol and water, and moreover contains a solvent and the(meth)acrylate which is used as a raw material in a content of 1 to 10%by mass or so, respectively.

When the above-mentioned lower layer is distilled, the solvent and the(meth)acrylate which is used as a raw material contained in the lowerlayer generate an azeotropic mixture together with the by-productalcohol. Therefore, the (meth)acrylate can be removed from the lowerlayer as an azeotropic mixture.

The condensate which is removed from the reactor A1 is fed to the liquidseparation apparatus 8, and water is added to the condensate to separatethe condensate into two layers of an upper layer and a lower layer. Thelower layer of the separated two layers is fed to the distillationapparatus B3 having the distillation column 4 through the pipe 5 f whichconnects the lower part of the liquid separation apparatus 8 with thedistillation apparatus B3. The lower layer fed to the distillationapparatus B3 is distilled in the distillation apparatus B3. When thislower layer is distilled, firstly vapor containing the (meth)acrylatewhich is used as a raw material, the by-product alcohol and the solventis generated by controlling the temperature at the top of thedistillation column 4 to a predetermined temperature, for example, 64°C. or lower in the case where the (meth)acrylate which is used as a rawmaterial is methyl (meth)acrylate, and then vapor containing theby-product alcohol which is generated as a major component by thetransesterification can be generated by controlling the temperature ofthe lower layer to a predetermined temperature, for example, 64° C. to66° C. in the case where the (meth)acrylate which is used as a rawmaterial is methyl (meth)acrylate. Each of the generated vapors can betaken out from the upper part of the distillation column 4.

As described above, the above-mentioned lower layer can be distilled byusing the distillation apparatus B3 having the distillation column 4.The distillation apparatus B3 can be any one of a batch typedistillation apparatus and a flow type distillation apparatus. When theabove-mentioned lower layer is distilled, the pressure can be any ofatmospheric pressure and reduced pressure. The number of theoreticalstages of the distillation column 4, which is used in distillation ispreferably 5 or more, more preferably 7 or more and furthermorepreferably 10 or more, from the viewpoint of efficient formation of anazeotropic mixture of a solvent, the (meth)acrylate which is used as araw material and a by-product alcohol, and is preferably 100 or less,more preferably 70 or less and furthermore preferably 50 or less, fromthe viewpoint of improvement in economic efficiency. In addition, whenthe above-mentioned lower layer is distilled, the distillationtemperature is preferably 20° C. or higher, more preferably 40° C. orhigher and furthermore preferably 50° C. or higher, and is preferably120° C. or lower, more preferably 110° C. or lower and furthermorepreferably 105° C. or lower, from the viewpoint of prevention ofpolymerization of the (meth)acrylate which is used as a raw material.

Since the vapor containing the (meth)acrylate which is used as a rawmaterial, the by-product alcohol and the solvent contains the solvent,the (meth)acrylate which is used as a raw material and the by-productalcohol, it is preferred that the vapor is condensed, and the resultingcondensate is used as a raw material which is used when thetransesterification reaction of the (meth)acrylate which is used as araw material and an alcohol corresponding to an objective (meth)acrylateis carried out, from the viewpoint of reduction of the amount of awaste. In addition, it is preferred that the above-mentioned vapor iscondensed, the resulting condensate is distilled to separate thecondensate from a by-product alcohol and water, and then the condensateis used as a raw material which is used when the transesterificationreaction of the (meth)acrylate which is used as a raw material and analcohol corresponding to an objective (meth)acrylate is carried out,from the viewpoint of effective use of the condensate without thecontamination of the by-product alcohol and water. The separatedby-product alcohol and water can be used, for example, as water which isadded to the condensate which is removed from the reactor A1. Inaddition, the by-product alcohol can be easily separated from water, forexample, by distillation purification and the like. Since the by-productalcohol which is separated from water which is contained in the residuecontains substantially little impurities other than water, theby-product alcohol can be used, for example, as an industrial rawmaterial, a solvent and the like, as well as an alcohol which is usuallyused.

When the transesterification reaction of the (meth)acrylate which isused as a raw material and the alcohol is carried out, the reactiontemperature is preferably 70° C. or higher and more preferably 75° C. orhigher, from the viewpoint of increase in reaction rate, and ispreferably 140° C. or lower, more preferably 130° C. or lower andfurthermore preferably 120° C. or lower, from the viewpoint ofprevention of polymerization of the (meth)acrylate which is used as araw material and an objective (meth)acrylate.

The atmosphere where the transesterification reaction of the(meth)acrylate which is used as a raw material and the alcohol iscarried out is preferably an atmosphere containing oxygen from theviewpoint of prevention of polymerization of the (meth)acrylate which isused as a raw material and an objective (meth)acrylate, and is morepreferably a gas having an oxygen concentration of from 5% by volume toan atmospheric concentration from the viewpoint of improvement insafety. The pressure of the atmosphere can be usually atmosphericpressure, and the pressure can be increased or reduced. For example,when the pressure of the atmosphere is reduced, there is an advantagesuch that a side reaction can be inhibited since the reflux temperaturecan be lowered.

In accordance with the progress of the transesterification reaction ofthe (meth)acrylate which is used as a raw material and an alcohol,generating rate of a by-product alcohol is lowered, and thetransesterification reaction can be terminated at the time when apredetermined reaction rate is achieved. The (meth)acrylate which isused as a raw material in the reactor A1 comes to disappear due to theazeotrope with a solvent. When the (meth)acrylate which is used as a rawmaterial disappears in the reactor A1, the temperature at the top of thedistillation column 2 finally attains to a boiling point of the solvent.Therefore, the disappearance of the (meth)acrylate which is used as araw material can be confirmed by the temperature at the top of thedistillation column 2. For example, the transesterification reaction ofthe (meth)acrylate which is used as a raw material and an alcohol can beterminated at the time when the temperature at the top of thedistillation column 2 attains to a temperature about 5° C. higher thanthe azeotropic temperature of the solvent and a by-product alcohol. Theend point of the transesterification reaction of the (meth)acrylatewhich is used as a raw material and an alcohol can be confirmed, forexample, by means of gas chromatography, liquid chromatography and thelike.

When the transesterification reaction of the (meth)acrylate which isused as a raw material and an alcohol is carried out, the reaction timecannot be absolutely determined because the reaction time differsdepending on the amounts of the (meth)acrylate which is used as a rawmaterial and the alcohol, a reaction temperature and the like.Therefore, the reaction time is usually adjusted so that an intendedreaction rate is achieved.

As described above, an objective (meth)acrylate can be obtained bycarrying out the transesterification reaction of the (meth)acrylatewhich is used as a raw material and an alcohol.

After the transesterification reaction of the (meth)acrylate which isused as a raw material and an alcohol corresponding to an objective(meth)acrylate is carried out, the resulting reaction mixture is heatedto take out a vapor containing an unreacted (meth)acrylate which is usedas a raw material from the upper part of the distillation column 2.According to the present invention, after the transesterificationreaction is carried out as mentioned above, a vapor containing anunreacted (meth)acrylate which is used as a raw material can be takenout from the upper part of the distillation column 2 by heating thereaction mixture included in the reactor A1. When the above-mentionedprocedures are employed, the (meth)acrylate which is used as a rawmaterial can be efficiently collected from the reactor A1.

After the transesterification reaction of the (meth)acrylate which isused as a raw material and an alcohol, when the reaction mixtureincluded in the reactor A1 is heated, the temperature cannot beabsolutely determined because the temperature differs depending on thekind of a solvent used. The temperature is usually controlled to atemperature when a transesterification reaction of the (meth)acrylatewhich is used as a raw material and an alcohol is carried out,preferably 70° C. or higher and more preferably 75° C. or higher, and ispreferably 140° C. or lower, more preferably 130° C. or lower andfurthermore preferably 120° C. or lower, from the viewpoint ofprevention of polymerization of the (meth)acrylate which is used as araw material and an objective (meth)acrylate. When the reaction mixtureincluded in the reactor A1 is heated, the pressure in the reactor A1 canbe controlled to atmospheric pressure. Therefore, there is no necessityto use an apparatus for pressurizing or reducing the pressure. Asoccasion demands, the pressure can be increased to a pressure higherthan the atmospheric pressure, or reduced to a pressure lower than theatmospheric pressure.

When the reaction mixture in the reactor A1 is heated, vapor isgenerated. The vapor can be taken out from the upper part, preferablythe top of the reactor A1, and the vapor can be cooled to collect as acondensate.

When the vapor which is generated by heating the reaction mixture in thereactor A1 is taken out from the reactor A1, the vapor contains a vaporof a solvent. Therefore, the solvent is taken out from the reactor A1together with the (meth)acrylate which is used as a raw material, andthereby the amount of the solvent remaining in the reactor A1 decreases.Accordingly, in order to efficiently carry out the azeotrope of the(meth)acrylate which is used as a raw material and a solvent, thesolvent can be added to the reactor A1 as occasion demands. The amountof solvent added is not particularly limited, and can be controlled toan amount which enables to carry out the azeotrope of the (meth)acrylatewhich is used as a raw material and the solvent.

The end point of the azeotrope of the (meth)acrylate which is used as araw material and the solvent is not particularly limited. In accordancewith the decrease of the amount of the (meth)acrylate which is used as araw material, the azeotropic temperature of the azeotrope approaches tothe boiling point of the solvent. Therefore, it is preferred to carryout the azeotrope until the temperature attains to the boiling point ofthe above-mentioned solvent from the viewpoint of efficient collectionof the (meth)acrylate which is used as a raw material.

The condensate collected in the above mainly contains the (meth)acrylatewhich is used as a raw material, a solvent and a by-product alcoholgenerated by transesterification. The amount of the by-product alcoholis very smaller than the amount of the collected (meth)acrylate which isused as a raw material and the amount of the solvent. Therefore, thecondensate can be effectively used as a (meth)acrylate which is used asa raw material when a transesterification reaction is newly carried out.

An objective (meth)acrylate exists in the reaction mixture in thereactor A1. The objective (meth)acrylate can be collected, for example,by taking out the reaction mixture from the lower part of the reactorA1. The reaction mixture contains a solvent which is used when atransesterification reaction is carried out, a slight amount of anunreacted (meth)acrylate and a by-product alcohol other than anobjective (meth)acrylate. Therefore, the objective (meth)acrylate can becollected from the reaction mixture by removing these components fromthe reaction mixture as occasion demands. The removal of the unreacted(meth)acrylate, the solvent and the by-product alcohol from the reactionmixture can be easily carried out, for example, by distillation,extraction and the like.

As described above, after transesterification is carried out to preparean objective (meth)acrylate by using the system for producing a(meth)acrylate shown in FIG. 1, the (meth)acrylate which is used as araw material, a solvent, a by-product alcohol and the like, remaining inthe reaction system can be efficiently collected and reused, and anobjective (meth)acrylate can be efficiently prepared.

FIG. 2 is a schematic drawing showing another embodiment of a system forproducing a (meth)acrylate according to the present invention.

The system for producing a (meth)acrylate shown in FIG. 2 has a reactorA1 having a distillation column 2, a distillation apparatus B3 having adistillation column 4 and a distillation apparatus C14 having adistillation column 13.

The reactor A1 having the distillation column 2 shown in FIG. 2 can bethe same as the reactor A1 having the distillation column 2 shown inFIG. 1.

In addition, the distillation apparatus B3 having the distillationcolumn 4 shown in FIG. 2 can be the same as the distillation apparatusB3 having the distillation column 4 shown in FIG. 1. Incidentally, thedistillation apparatus B3 can be provided with, for example, a heatingapparatus 15 such as a reboiler for heating contents in the distillationapparatus B3 as occasion demands.

The condensate removed from the reactor A1 is fed to the separationapparatus 8, and water is added to the condensate, to separate thecondensate into two layers of an upper layer and a lower layer in thesame manner as in the above-mentioned embodiment of the system forproducing a (meth)acrylate shown in FIG. 1. The lower layer of theseparated two layers is fed to the distillation apparatus B3 having thedistillation column 4 through a pipe 5 f, and distilled.

It is preferred that the position of the distillation column 4 where theabove-mentioned lower layer is fed to the distillation column 4 is amiddle stage of the distillation column 4 from the viewpoint ofefficient separation of a solvent contained in the lower layer from aby-product alcohol and water generated as a by-product. Incidentally,the middle stage of the distillation column 4 means a central stage ofthe multistage distillation column. When the distillation column 4 is,for example, a distillation column having a number of theoretical stagesof 15, 6 to 9 stages of the distillation column correspond to the middlestage of the distillation column.

When the above-mentioned lower layer is distilled, firstly vaporcontaining the (meth)acrylate which is used as a raw material, aby-product alcohol and a solvent is generated by controlling thetemperature at the top of the distillation column 4 to a predeterminedtemperature, for example, 64° C. or lower in the case where the(meth)acrylate which is used as a raw material is methyl (meth)acrylate,and then vapor containing the by-product alcohol which is generated bythe transesterification reaction as a major component can be generatedby controlling the temperature of the lower layer to a predeterminedtemperature, for example, 64° C. to 66° C. in the case where the(meth)acrylate which is used as a raw material is methyl (meth)acrylate.Each of the generated vapors can be taken out from the upper part of thedistillation column 4.

When the above-mentioned lower layer is distilled, the pressure can beany of atmospheric pressure and reduced pressure. The number oftheoretical stages of the distillation column 4 which is used indistillation is preferably 5 or more, more preferably 7 or more andfurthermore preferably 10 or more, from the viewpoint of efficientformation of an azeotropic mixture of a solvent, the (meth)acrylatewhich is used as a raw material and a by-product alcohol, and ispreferably 100 or less, more preferably 70 or less and furthermorepreferably 50 or less, from the viewpoint of improvement in economicefficiency. In addition, when the above-mentioned lower layer isdistilled, the distillation temperature is preferably 20° C. or higher,more preferably 40° C. or higher and furthermore preferably 50° C. orhigher, and is preferably 120° C. or lower, more preferably 110° C. orlower and furthermore preferably 105° C. or lower, from the viewpoint ofprevention of polymerization of the (meth)acrylate which is used as araw material.

The vapor containing the (meth)acrylate which is used as a raw material,a by-product alcohol and a solvent contains the solvent, the(meth)acrylate which is used as a raw material and the by-productalcohol. Therefore, the upper part, preferably the top of thedistillation column 4 of the distillation apparatus B3 is connected witha condensing apparatus 9 through a pipe 10 a. The condensing apparatus 9is connected with a switching apparatus 11 through a pipe 10 b, and theswitching apparatus 11 is connected with the upper part, preferably thetop of the distillation column 4 through a pipe 10 c in order to refluxa part of the condensate obtained in the condensing apparatus 9 to theupper part, preferably the top of the distillation column 4.

The condensing apparatus 9 is connected with the switching apparatus 11through the pipe 10 b, and the switching apparatus 11 is connected witha collecting unit 12 through a pipe 10 d in order to collect thecondensate remaining in the condensing apparatus 9. The condensateobtained by condensing the above-mentioned vapor in the condensingapparatus 9 mainly contains a solvent, the (meth)acrylate which is usedas a raw material and a by-product alcohol. Therefore, theabove-mentioned condensate can be effectively used by collecting thecondensate in the collecting unit 12, and returning the condensatecollected in the collecting unit 12 to the reactor A1.

A liquid mainly containing water and the by-product alcohol exists inthe lower part or the bottom of the distillation apparatus B3 having thedistillation column 4. The liquid is fed to the distillation apparatusC14 having the distillation column 13 through a pipe 16 which isconnected with the distillation apparatus B3 at the lower part or thebottom of the distillation apparatus B3.

The distillation apparatus C14 having the distillation column 13 can bethe same as the distillation apparatus B3 having the distillation column4 shown in FIG. 1. Incidentally, the distillation apparatus C14 can beprovided with, for example, a heating apparatus 17 such as a reboiler inorder to heat the contents in the distillation apparatus C14 as occasiondemands.

It is preferred that the position of the distillation column 13 wherethe above-mentioned liquid is fed is a middle stage of the distillationcolumn 13 from the viewpoint of efficient separation of water containedin the liquid from a by-product alcohol. Incidentally, as describedabove, the middle stage of the distillation column 13 means a stagepositioned at around the center of the multistage distillation column.When the distillation column 13 is, for example, a distillation columnhaving a number of theoretical stages of 15, 6 to 9 stages of thedistillation column correspond to the middle stage of the distillationcolumn.

When the above-mentioned liquid is distilled, vapor containing aby-product alcohol and water vapor can be generated, and the generatedvapor can be taken out from the top of the distillation column 13 bycontrolling the temperature of the top of the distillation column 13 toa predetermined temperature, for example, 64° C. to 66° C. in the casewhere the by-product alcohol is methanol.

The distillation apparatus C14 can be any one of a batch typedistillation apparatus and a flow type distillation apparatus. Apreferred distillation apparatus C14 having the distillation column 13includes, for example, a packed column, a tray type distillation columnand the like, and the present invention is not limited only to thoseexemplified ones. A filler used in the packed column includes, forexample, Helipack, McMahon, Cascade Mini Ring and the like, and thepresent invention is not limited only to those exemplified ones. Thetray type distillation column includes, for example, a packeddistillation column, an Oldershaw distilling column, a Lift Traydistillation column and the like, and the present invention is notlimited only to those exemplified ones.

When the above-mentioned liquid is distilled, the pressure can be any ofatmospheric pressure and reduced pressure. The number of theoreticalstages of the distillation column 13 which is used in distillation ispreferably 5 or more, more preferably 7 or more and furthermorepreferably 10 or more, from the viewpoint of efficient formation of anazeotropic mixture of a by-product alcohol and water, and is preferably100 or less, more preferably 70 or less and furthermore preferably 50 orless, from the viewpoint of improvement in economic efficiency. Inaddition, when the above-mentioned liquid is distilled, the distillationtemperature is preferably 20° C. or higher, more preferably 40° C. orhigher and furthermore preferably 50° C. or higher, and is preferably120° C. or lower, more preferably 110° C. or lower and furthermorepreferably 105° C. or lower, from the viewpoint of improvement inchemical stability of an objective (meth)acrylate.

In order to separate the by-product alcohol contained in theabove-mentioned liquid from water, the upper part, preferably the top ofthe distillation column 13 of the distillation apparatus C14 isconnected with a condensing apparatus 19 through a pipe 18 a. In orderto reflux a part of the condensate obtained in the condensing apparatus19 to the upper part, preferably the top of the distillation column 13,the condensing apparatus 19 is connected with a switching apparatus 20through a pipe 18 b, and the switching apparatus 20 is connected withthe upper part, preferably the top of the distillation column 13 througha pipe 18 c by operating the switching apparatus 20.

The switching apparatus 20 includes, for example, a switching valve, areflux distributor, a solenoid valve and the like, and the presentinvention is not limited only to those exemplified ones.

The condensate obtained by condensing the above-mentioned vapor in thecondensing apparatus 19 mainly contains a by-product alcohol. When thisby-product alcohol is collected in a collecting unit 21, the condensingapparatus 19 is connected with the switching apparatus 20 through thepipe 18 b, and the switching apparatus 20 is connected with thecollecting unit 21 through a pipe 18 d by operating the switchingapparatus 20. The by-product alcohol collected in the collecting unit 21can be effectively used, for example, as a fuel, a raw material forpreparing various organic compounds, and the like. The collecting unit21 can be a so-called receiver.

In the lower part or the bottom of the distillation apparatus C14 havingthe distillation column 13, water is mainly exists. The water can beeffectively used in the liquid separation apparatus 8 of the reactor A1by connecting the lower part or the bottom of the distillation apparatusC14 with the pipe 5 d through a pipe 18 e. The pipe 18 e can be easilyconnected with the pipe 5 d by means of, for example, a three-way cock(not shown in the figure) and the like.

As described above, when the system for producing a (meth)acrylate shownin FIG. 2 is employed, after the preparation of a (meth)acrylate by thetransesterification, a (meth)acrylate which is used as a raw material, asolvent, an alcohol generated as a by-product and the like which areremaining in a reaction system can be efficiently collected and reused,and an objective (meth)acrylate can be efficiently prepared.

Incidentally, the (meth)acrylate which is used as a raw material isusually malodorous. Therefore, when the (meth)acrylate is exposed to theair, strong bad smell is emitted to the air. Therefore, it has beendesired that the (meth)acrylate is not exposed to the air, or that theamount of the (meth)acrylate exposed to the air is reduced as much aspossible.

To the contrary, according to the present invention, since a(meth)acrylate used as a raw material remains in a reaction mixtureafter transesterification, and the remaining (meth)acrylate can begently and easily removed from a reaction mixture by the azeotrope ofthe (meth)acrylate which can be used as a raw material and a solventunder atmospheric pressure, the amount of the (meth)acrylate which isused as a raw material, exhausted to the air can be reduced as much aspossible.

Therefore, it can be said that the system for producing a (meth)acrylateof the present invention is an environment-friendly system whichconsiders environmental impact.

Incidentally, an exhaust port of the reactor A1 can be equipped with analkali scrubber and the like as occasion demands in order to adsorb the(meth)acrylate which is used as a raw material, and inhibit theexhaustion of the (meth)acrylate to the air.

In addition, it is sometimes desired that a (meth)acrylate which is usedas a raw material is not is contaminated in an objective (meth)acrylatedepending on the kind, use and the like of the objective (meth)acrylate.The system for producing a (meth)acrylate of the present invention isalso useful as a system which avoids the contamination of a(meth)acrylate which is used as a raw material in an objective(meth)acrylate.

Furthermore, when the system for producing a (meth)acrylate of thepresent invention is employed, a by-product alcohol can be collected ina high purity, a by-product (meth)acrylate generated bytransesterification can be effectively used, and by-product water alsocan be effectively used. Therefore, the system for producing a(meth)acrylate of the present invention is a system (apparatus) which isexcellent in industrial productivity of a (meth)acrylate.

In addition, since the system for producing a (meth)acrylate of thepresent invention is a so-called closed system, the amount of aby-product exhausted to the outside of the reaction system can bereduced, and a yield of an objective (meth)acrylate can be improved.

The (meth)acrylate prepared by using the system for producing a(meth)acrylate of the present invention is useful, for example, as a rawmaterial for a (meth)acrylic resin, a surfactant, an adhesive, a paint,and the like.

EXAMPLES

Next, the present invention will be more specifically described based onworking examples. However, the present invention will not be limitedonly to those examples.

In the following examples, the yield of an objective (meth)acrylate wasdetermined based on the ratio of the actually resulting amount of theobjective (meth)acrylate to the theoretically resulting amount of theobjective (meth)acrylate.

In addition, each amount of a raw material alcohol, an objective(meth)acrylate obtained from the raw material alcohol, a solvent and a(meth)acrylate which was used as a raw material in the reaction mixtureobtained in the following examples was determined based on an areapercentage in gas chromatography (hereafter referred to as GC) obtainedby using a GC analyzer (manufactured by Agilent Technologies Ltd.,detector: FID, column capillary: DB-1: 30 m).

Example 1

A system for producing a (meth)acrylate shown in FIG. 1 was used. As areactor A having a distillation column, a 2-liter four-necked flaskhaving a 20-stage Oldershaw distillation column (number of theoreticalstages: 15) equipped with a condensing apparatus at its top and having aside tube, and an air intake tube was used. The flask was charged with694 g (8.06 moles) of methyl acrylate, 552 g (6.20 moles) ofN,N-dimethylaminoethanol, 1.76 g of phenothiazine, 22.1 g of dibutyltinoxide and 100 g of cyclohexane. A transesterification reaction wascarried out while blowing air into the flask from the air intake tube ata flow rate of 20 mL/min. More specifically, vapor which was taken outfrom the top of the distillation column was condensed in the condensingapparatus, a part of the resulting condensate was refluxed to the top ofthe distillation column, and the remaining condensate was removed fromthe flask. The amount of the condensate which was removed from the topof the distillation column was adjusted to control the temperature ofthe top of the distillation column to an azeotropic temperature ofmethyl alcohol and cyclohexane of 54° C. to 56° C.

The condensate which was removed from the top of the distillation columnin an amount of 700 g was mixed with 200 g of water at a temperature of20° C., and the resulting mixed solution was fed to a decanter. Thismixed solution was separated into two layers of an upper layer and alower layer. Since methyl alcohol which was contained in the condensatewas extracted with water, the methyl alcohol was contained in the lowerlayer, and the cyclohexane which had been included in the condensate wascontained in the upper layer.

The amount of the above-mentioned lower layer was 410 g. The lower layercontained 47.0% by mass (193 g) of methyl alcohol, 0.5% by mass (2 g) ofcyclohexane, 3.6% by mass (15 g) of methyl acrylate and 48.9% by mass(200 g) of water.

On the other hand, the above-mentioned upper layer was effectively usedby feeding the upper layer to the distillation column at the middlestage of the distillation column where a 10th stage was provided fromthe bottom of the distillation column.

A transesterification reaction of methyl acrylate andN,N-dimethylaminoethanol was carried out while properly addingcyclohexane to the flask so that the reaction temperature was 85° C. to102° C. When 4 hours passed from the initiation of the reaction, thetransesterification reaction was terminated. After the termination ofthe reaction, the amount of methyl acrylate contained in the reactionmixture which was obtained by the above-mentioned transesterificationreaction was 160 g.

After the termination of the reaction, a reaction mixture obtained bythe above-mentioned transesterification reaction was further heated, anda reflux ratio was controlled to 10 to 15. A vapor was taken out fromthe top of the distillation column, and the vapor was condensed to givea condensate. At that time, cyclohexane was added to the flask so thatthe temperature of the reaction mixture included in the flask wasmaintained to 85° C. to 100° C. While taking out the condensate from thetop of the distillation column, the temperature at the top of thedistillation column was gradually increased. The distillation wascontinued until the temperature at the top of the distillation columnattained to a boiling point of cyclohexane of 80° C.

As a result, the content of methyl acrylate in the reaction mixtureincluded in the flask was at most 0.1% by mass. The condensate was takenout from the top of the distillation column, and collected. The amountof the collected condensate was 490 g, and this condensate contained 5 gof methanol, 145 g of methyl acrylate and 340 g of cyclohexane. Thiscondensate contained most of the methyl acrylate which was used in anexcessive amount. This collected condensate could be used when atransesterification reaction of methyl acrylate andN,N-dimethylaminoethanol was carried out. From this fact, it wasconfirmed that loss of methyl acrylate could be prevented by using theabove-mentioned condensate when a transesterification reaction of methylacrylate and N,N-dimethylaminoethanol was carried out.

As a result of the preparation of N,N-dimethylaminoethyl acrylate asdescribed above, the yield of N,N-dimethylaminoethyl acrylate was 852 g(yield on the basis of N,N-dimethylaminoethanol: 96% by mass, yield onthe basis of the amount of methyl acrylate used: 73.8% by mass, yield inthe case where methyl acrylate which was collected by the azeotrope withcyclohexane after the termination of the reaction was reused: 93.3% bymass).

From the above results, when a reactor A is used, it can be seen that acondensate taken out from the upper part of the distillation column canbe efficiently used by mixing the condensate with water, separating theresulting mixed solution into two layers, and feeding the resultingupper layer to the distillation column, that a condensate obtained byheating a reaction mixture prepared by transesterification, andcollecting from the top of the distillation column can be effectivelyused in a new transesterification reaction, and that an objectiveN,N-dimethylaminoethyl acrylate can be prepared in a high yield.

Next, as a distillation apparatus B, a 1-liter four-necked flask havinga 10-stage Oldershaw distillation column (number of theoretical stages:7) equipped with a condensing apparatus at its top and having a sidetube, and an air intake tube was used. The flask was charged with thelower layer obtained in the above.

A distillation was carried out while refluxing in a reflux ratio of 10to 15. When the temperature at the top of the distillation column was64° C. or lower, a fraction A was collected. As a result, the amount ofthe collected fraction A was 40 g, and this fraction A was composed of62.1% by mass (25 g) of methyl alcohol, 32.5% by mass (13 g) of methylacrylate, 5.3% by mass (2 g) of cyclohexane and 0.1% by mass of water.This fraction A could be used when a transesterification reaction ofmethyl acrylate and N,N-dimethylaminoethanol was carried out.

The above-mentioned distillation was continued in a reflux ratio of 5 to10. When the temperature at the top of the distillation column was 64°C. to 66° C., a fraction B was collected. As a result, the amount of thecollected fraction B was 167 g. This fraction B was composed of 99.9% bymass of methyl alcohol and 0.1% by mass of water, and it was notconfirmed that methyl acrylate was included.

The above-mentioned fraction B was analyzed by the GC. As a result, nocomponent other than methyl alcohol and a slight amount of water wasdetected. Therefore, it was confirmed that the fraction B could beeffectively used as an industrial raw material, a solvent and the like.In addition, since methyl acrylate was not detected in the fraction B bythe GC, it was confirmed that loss of methyl acrylate was little, andtherefore a yield of N,N-dimethylaminoethyl acrylate was not adverselyaffected.

In addition, 203 g of the residual solution in the flask was composed of3% by mass of methyl alcohol and 97% by mass of water, and a componentother than these compounds was not detected by the GC. Since theresidual solution mainly contained water, the residual solution could beused as water which was used in mixing a condensate with water inExample 1.

From the above results, it can be seen that there can be effectivelyused a lower layer obtained by mixing a condensate which was taken outfrom the top of the distillation column of the above-mentioned reactor Awith water, and separating the resulting mixed solution into two layers.

Example 2

A reactor A which was the same kind as that used in Example 1 was used.The flask was charged with 517 g (6.00 moles) of methyl acrylate, 651 g(5.00 moles) of n-octyl alcohol, 1.76 g of phenothiazine, 0.72 g oftetramethyltitanium and 117 g of n-hexane. A transesterificationreaction was carried out while blowing air into the flask from the airintake tube at a flow rate of 20 mL/min. More specifically, a vaporwhich was taken out from the top of the distillation column wascondensed, a part of the resulting condensate was refluxed to the top,and the remaining condensate was removed from the flask. The temperatureat the top of the distillation column was controlled to an azeotropictemperature of methyl alcohol and n-hexane of 48° C. to 50° C. byadjusting the amount of the condensate removed from the flask.

The condensate which was removed from the top of the distillation columnin an amount of 549 g was mixed with 100 g of water at a temperature of20° C., and the resulting mixed solution was introduced to a decanter.This mixed solution was separated into two layers of an upper layer anda lower layer. Since methyl alcohol contained in the condensate wasextracted with water, the methyl alcohol was contained in the lowerlayer, and the n-hexane included in the condensate was contained in theupper layer.

The amount of the above-mentioned lower layer was 257 g, and the lowerlayer contained 56.4% by mass (145 g) of methyl alcohol, 1.6% by mass (4g) of n-hexane, 3.1% by mass (8 g) of methyl acrylate and 38.9% by mass(100 g) of water.

On the other hand, the above-mentioned upper layer was effectively usedby feeding the upper layer to the distillation column at the middlestage of the distillation column where a 10th stage was provided fromthe bottom of the distillation column.

The reaction temperature in the transesterification reaction of methylacrylate and n-octyl alcohol was 90° C. to 110° C. When 8 hours passedfrom the initiation of the reaction, the transesterification reactionwas terminated. After the termination of the reaction, the amount ofmethyl acrylate contained in the reaction mixture which was obtained bythe above-mentioned transesterification reaction was 86 g.

After the termination of the reaction, a reaction mixture obtained bythe above-mentioned transesterification reaction was further heated in areflux ratio of 10 to 15. A vapor was taken out from the top of thedistillation column, and the vapor was condensed to collect acondensate. At that time, n-hexane was added to the flask so that thetemperature of the reaction mixture included in the flask was maintainedto 90° C. to 110° C. While taking out the condensate from the top of thedistillation column, the temperature at the top of the distillationcolumn was gradually increased. The distillation was continued until thetemperature at the top of the distillation column attained to a boilingpoint of n-hexane of 68° C.

As a result, the content of methyl acrylate in the reaction mixtureincluded in the flask was at most 0.2% by mass. In addition, the amountof the condensate taken out from the top of the distillation column andcollected was 392 g. This condensate contained 3.8% by mass (15 g) ofmethanol, 18.6% by mass (73 g) of methyl acrylate and 77.6% by mass (304g) of n-hexane. This condensate contained most of the methyl acrylateused in an excessive amount. This collected condensate could be usedwhen a transesterification reaction of methyl acrylate and n-octylalcohol was carried out. From this fact, it was confirmed that loss ofmethyl acrylate could be prevented by using the above-mentionedcondensate when a transesterification reaction of methyl acrylate andn-octyl alcohol is carried out.

As a result of the preparation of n-octyl acrylate as described above,the yield of n-octyl acrylate was 912 g (yield on the basis of n-octylacrylate: 99.0% by mass; yield on the basis of the amount of methylacrylate used: 82.5% by mass; yield in the case where methyl acrylatewhich was collected by azeotrope with n-hexane after the termination ofthe reaction was reused: 96.0% by mass).

Next, as a distillation apparatus B, a 2-liter four-necked flask havinga 10-stage Oldershaw distillation column (number of theoretical stages:7) equipped with a condensing apparatus at its top and having a sidetube, and an air intake tube was used. The flask was charged with thelower layer obtained in the above.

A distillation was carried out while refluxing in a reflux ratio of 10to 15. When the temperature at the top of the distillation column was64° C. or lower, a fraction A was collected. As a result, the amount ofthe collected fraction A was 32 g, and this fraction A was composed of62.5% by mass (20 g) of methyl alcohol, 25.0% by mass (8 g) of methylacrylate, 12.5% by mass (4 g) of n-hexane and 0.1% by mass of water.This fraction A could be used when a transesterification reaction ofmethyl acrylate and n-octyl alcohol was carried out.

The above-mentioned distillation was continued in a reflux ratio of 5 to10. When the temperature of the top of the distillation column was 64°C. to 66° C., a fraction B was collected. As a result, the amount of thecollected fraction B was 122 g. This fraction B contained 99.9% by mass(122 g) of methyl alcohol and 0.1% by mass of water, and it was notconfirmed that methyl acrylate was included.

Since the above-mentioned fraction B did not contain a component otherthan methyl alcohol and a slight amount of water, it was confirmed thatthe fraction B could be effectively used as an industrial raw material,a solvent and the like. In addition, since methyl acrylate was notdetected in the fraction B by the GC, it was confirmed that loss ofmethyl acrylate was little, and therefore a yield of n-octyl acrylatewas not adversely affected.

In addition, 103 g of the residual solution in the flask was composed of3% by mass (3 g) of methyl alcohol and 97% by mass (100 g) of water, anda component other than these compounds was not detected by the GC. Sincethe residual solution mainly contained water, the residual solutioncould be used as water which was used in mixing a condensate with water.

Example 3

A reactor A which was the same kind as that used in Example 1 was used.The flask was charged with 430 g (5.0 moles) of methyl acrylate, 675 g(7.5 moles) of 1,4-butanediol, 0.72 g of phenothiazine, 3.6 g ofdioctyltin oxide and 100 g of cyclohexane. A transesterificationreaction was carried out while blowing air into the flask from the airintake tube at a flow rate of 20 mL/min. More specifically, vapor whichwas taken out from the top of the distillation column was condensed, apart of the resulting condensate was refluxed to the top, and theremaining condensate was removed from the reactor A. The temperature atthe top of the distillation column was controlled to an azeotropictemperature of methyl alcohol and cyclohexane of 54° C. to 56° C. byadjusting the amount of the condensate removed from the flask.

The condensate which was removed from the top of the distillation columnin an amount of 490 g was mixed with 140 g of water at a temperature of20° C., and the resulting mixed solution was introduced to a decanter.This mixed solution was separated into two layers of an upper layer anda lower layer. Since methyl alcohol contained in the condensate wasextracted with water, the methyl alcohol was contained in the lowerlayer, and the cyclohexane included in the condensate was contained inthe upper layer.

The amount of the above-mentioned lower layer was 303 g, and the lowerlayer contained 48.7% by mass (148 g) of methyl alcohol, 1.6% by mass (5g) of cyclohexane, 3.3% by mass (10 g) of methyl acrylate and 46.4% bymass (140 g) of water.

On the other hand, the above-mentioned upper layer was effectively usedby feeding the upper layer to the distillation column at the middlestage of the distillation column where a 10th stage was provided fromthe bottom of the distillation column.

A transesterification reaction of methyl acrylate and 1,4-butanediol wascarried out while properly adding cyclohexane to the flask so that thereaction temperature was 85° C. to 100° C. When 8 hours passed from theinitiation of the reaction, the transesterification reaction wasterminated. After the termination of the reaction, the amount of methylacrylate contained in the reaction mixture which was obtained by theabove-mentioned transesterification reaction was 20 g.

After the termination of the reaction, a reaction mixture obtained bythe above-mentioned transesterification reaction was further heated in areflux ratio of 10 to 15. A vapor was taken out from the top of thedistillation column, and the vapor was condensed to collect acondensate. At that time, cyclohexane was added to the flask so that thetemperature of the reaction mixture included in the flask was maintainedto 85° C. to 100° C. While taking out the condensate from the top of thedistillation column, the temperature at the top of the distillationcolumn gradually increased. The distillation was continued until thetemperature at the top of the distillation column attained to a boilingpoint of cyclohexane of 80° C.

As a result, the content of methyl acrylate in the reaction mixtureincluded in the flask was at most 0.2% by mass. In addition, the amountof the condensate taken out from the top of the distillation column andcollected was 75 g. This condensate contained 5 g of methanol, 10 g ofmethyl acrylate and 60 g of cyclohexane. This condensate contained mostof the methyl acrylate used in an excessive amount. This collectedcondensate could be used when a transesterification reaction of methylacrylate and 1,4-butanediol was carried out. From this fact, it wasconfirmed that loss of methyl acrylate could be prevented by using theabove-mentioned condensate when a transesterification reaction of methylacrylate and 1,4-butanediol is carried out.

As a result of the preparation of 4-hydroxybutyl acrylate as describedabove, the obtained reaction mixture contained 496 g of 4-hydroxybutylacrylate, 131 g of 1,4-butanediol diacrylate and 305 g of1,4-butanediol. The 4-hydroxybutyl acrylate contained in this reactionmixture could be separated by extracting the reaction mixture,distilling the reaction mixture or adsorbing with an adsorption column.

Next, as a distillation apparatus B, a 1-liter four-necked flask havinga 10-stage Oldershaw distillation column (number of theoretical stages:7) equipped with a condensing apparatus at its top and having a sidetube, and an air intake tube was used. The flask was charged with thelower layer obtained in the above.

A distillation was carried out while refluxing in a reflux ratio of 10to 15. When the temperature at the top of the distillation column was64° C. or lower, a fraction A was collected. As a result, the amount ofthe collected fraction A was 42 g, and this fraction A was composed of64.3% by mass (27 g) of methyl alcohol, 23.8% by mass (10 g) of methylacrylate, 12.5% by mass (5 g) of cyclohexane and 0.1% by mass (0.04 g)of water. This fraction A could be used when a transesterificationreaction of methyl acrylate and 1,4-butanediol was carried out.

The above-mentioned distillation was continued in a reflux ratio of 5 to10. When the temperature at the top of the distillation column was 64°C. to 65° C., a fraction B was collected. As a result, the amount of thecollected fraction B was 118 g. This fraction B was composed of 99.9% bymass of methyl alcohol and 0.1% by mass of water, and it was notconfirmed that methyl acrylate was included.

Since the above-mentioned fraction B did not contain a component otherthan methyl alcohol and a slight amount of water, it was confirmed thatthe fraction B could be effectively used as an industrial raw material,a solvent and the like. In addition, since methyl acrylate was notdetected in the fraction B by the GC, it was confirmed that loss ofmethyl acrylate was little, and therefore a yield of 4-hydroxybutylacrylate was not adversely affected.

In addition, 142 g of the residual solution in the flask was composed of3% by mass of methyl alcohol and 97% by mass of water, and a componentother than these compounds was not detected by the GC. Since theresidual solution mainly contained water, the residual solution could beused as water which was used in mixing a condensate with water.

Example 4

A transesterification reaction was carried out in the same manner as inExample 1 except that the same reactor A as used in Example 1 wascharged with 780.9 g (7.80 moles) of methyl methacrylate, 372.4 g (6.00moles) of N,N-dimethylaminoethanol and 1.89 g of phenothiazine. Afterthe termination of the reaction, the amount of methyl methacrylatecontained in the reaction mixture which was obtained by thetransesterification reaction was 178 g.

After cyclohexane was added to the flask, and 175 g of unreacted methylmethacrylate was collected, the content of methyl methacrylate in thereaction mixture included in the flask was determined. As a result, thecontent of methyl methacrylate was at most 0.1% by mass.

Next, the lower layer of the decanter was distilled in the same manneras in Example 1, and 5 g of a fraction A was collected. This fraction Awas composed of 86.9% by mass of methyl alcohol, 13.0% by mass ofcyclohexane and 0.1% by mass of water. This fraction A could be usedwhen a transesterification reaction of methyl methacrylate andN,N-dimethylaminoethanol was carried out. Subsequently, a fraction B wascollected in the same manner as in Example 1, and its components wereexamined. As a result, this fraction B was composed of 99.9% by mass ofmethyl alcohol and 0.1% by mass of water.

Example 5

A transesterification reaction was carried out in the same manner as inExample 1 except that the same reactor A as used in Example 1 wascharged with 1041.2 g (10.4 moles) of methyl methacrylate, 248.3 g (4.00moles) of ethylene glycol, 1.59 g of phenothiazine and 0.96 g of lithiumhydroxide. After the termination of the reaction, the amount of methylmethacrylate contained in the reaction mixture which was obtained by thetransesterification reaction was 235 g.

After cyclohexane was added to the flask, and 233 g of unreacted methylmethacrylate was collected, the content of methyl methacrylate in thereaction mixture included in the flask was examined. As a result, thecontent of methyl methacrylate was at most 0.1% by mass.

Next, the lower layer of the decanter was distilled in the same manneras in Example 1, and 5 g of a fraction A was collected. This fraction Awas composed of 86.9% by mass of methyl alcohol, 13.0% by mass ofcyclohexane and 0.1% by mass of water. This fraction A could be usedwhen a transesterification reaction of methyl methacrylate and ethyleneglycol was carried out. Subsequently, a fraction B was collected in thesame manner as in Example 1, and its components were examined. As aresult, this fraction B was composed of 99.9% by mass of methyl alcoholand 0.1% by mass of water.

Example 6

A transesterification reaction was carried out in the same manner as inExample 1 except that 633.2 g (6.20 moles) of tetrahydrofurfuryl alcoholwas used in place of N,N-dimethylaminoethanol in Example 1. After thetermination of the reaction, the amount of methyl acrylate contained inthe reaction mixture which was obtained by the transesterificationreaction was 147 g.

After cyclohexane was added to the flask, and 146 g of unreacted methylacrylate was collected, the content of methyl acrylate in the reactionmixture included in the flask was examined. As a result, the content ofmethyl acrylate was at most 0.1% by mass.

Next, the lower layer of the decanter was distilled in the same manneras in Example 1. As a result, a fraction A was composed of 62.3% by massof methyl alcohol, 32.1% by mass of methyl acrylate, 5.5% by mass ofcyclohexane and 0.1% by mass of water. This fraction A could be usedwhen a transesterification reaction of methyl acrylate andtetrahydrofurfuryl alcohol was carried out. Subsequently, a fraction Bwas collected in the same manner as in Example 2, and its componentswere examined. As a result, this fraction B was composed of 99.9% bymass of methyl alcohol and 0.1% by mass of water, and it was notconfirmed that methyl acrylate was included.

Example 7

A transesterification reaction was carried out in the same manner as inExample 1 except that 805.0 g (6.00 moles) of diethylene glycolmonoethyl ether was used in place of N,N-dimethylaminoethanol inExample 1. After the termination of the reaction, the amount of methylacrylate contained in the reaction mixture which was obtained by thetransesterification reaction was 140 g.

After cyclohexane was added to the flask, and 138 g of unreacted methylacrylate was collected, the content of methyl acrylate in the reactionmixture included in the flask was examined. As a result, the content ofmethyl acrylate was at most 0.1% by mass.

Next, the lower layer of the decanter was distilled in the same manneras in Example 1. As a result, a fraction A was composed of 62.3% by massof methyl alcohol, 32.3% by mass of methyl acrylate, 5.3% by mass ofcyclohexane and 0.1% by mass of water. This fraction A could be usedwhen a transesterification reaction of methyl acrylate and diethyleneglycol monoethyl ether was carried out. Subsequently, a fraction B wascollected in the same manner as in Example 2, and its components wereexamined. As a result, this fraction B was composed of 99.9% by mass ofmethyl alcohol and 0.1% by mass of water, and it was not confirmed thatmethyl acrylate was included.

Example 8

A transesterification reaction was carried out in the same manner as inExample 1 except that 894.8 g (5.20 moles) of methyl acrylate, 472.7 g(4.00 moles) of 1,6-hexane diol and 3.7 g of dioctyltin oxide were usedin Example 1. After the termination of the reaction, the amount ofmethyl acrylate contained in the reaction mixture which was obtained bythe transesterification reaction was 189 g.

After cyclohexane was added to the flask, and 188 g of unreacted methylacrylate was collected, the content of methyl acrylate in the reactionmixture included in the flask was examined. As a result, the content ofmethyl acrylate was at most 0.1% by mass.

Next, the lower layer of the decanter was distilled in the same manneras in Example 1. As a result, a fraction A was composed of 62.1% by massof methyl alcohol, 32.4% by mass of methyl acrylate, 5.4% by mass ofcyclohexane and 0.1% by mass of water. This fraction A could be usedwhen a transesterification reaction of methyl acrylate and 1,6-hexanediol was carried out. Subsequently, a fraction B was collected in thesame manner as in Example 1, and its components were examined. As aresult, this fraction B was composed of 99.9% by mass of methyl alcoholand 0.1% by mass of water, and it was not confirmed that methyl acrylatewas included.

Example 9

A transesterification reaction was carried out in the same manner as inExample 1 except that 1006.7 g (11.7 moles) of methyl acrylate, 402.5 g(3.00 moles) of trimethylolpropane and 8.4 g of dioctyltin oxide wereused in Example 1. After the termination of the reaction, the amount ofmethyl acrylate contained in the reaction mixture which was obtained bythe transesterification reaction was 216 g.

After cyclohexane was added, and 214 g of unreacted methyl acrylate wascollected, the content of methyl acrylate in the reaction mixtureincluded in the flask was examined. As a result, the content of methylacrylate was at most 0.1% by mass.

Next, the lower layer of the decanter was distilled in the same manneras in Example 1. As a result, a fraction A was composed of 62.1% by massof methyl alcohol, 32.3% by mass of methyl acrylate, 5.5% by mass ofcyclohexane and 0.1% by mass of water. This fraction A could be usedwhen a transesterification reaction of methyl acrylate andtrimethylolpropane was carried out. Subsequently, a fraction B wascollected in the same manner as in Example 1, and its components wereexamined. As a result, this fraction B was composed of 99.9% by mass ofmethyl alcohol and 0.1% by mass of water, and it was not confirmed thatmethyl acrylate was included.

Example 10

A transesterification reaction was carried out in the same manner as inExample 1 except that 559.3 g (6.5 moles) of methyl acrylate, 1041.5 g(5.00 moles) of 2-ethyl-2-methyl-1,3-dioxolane-4-methanol and 4.7 g ofdioctyltin oxide were used in Example 1. After the termination of thereaction, the amount of methyl acrylate contained in the reactionmixture which was obtained by the transesterification reaction was 117g.

After cyclohexane was added to the flask, and 116 g of unreacted methylacrylate was collected, the content of methyl acrylate in the reactionmixture included in the flask was examined. As a result, the content ofmethyl acrylate was at most 0.1% by mass.

Next, the lower layer of the decanter was distilled in the same manneras in Example 1. As a result, a fraction A was composed of 62.5% by massof methyl alcohol, 32.1% by mass of methyl acrylate, 5.3% by mass ofcyclohexane and 0.1% by mass of water. This fraction A could be usedwhen a transesterification reaction of methyl acrylate and2-ethyl-2-methyl-1,3-dioxolane-4-methanol was carried out. Subsequently,a fraction B was collected in the same manner as in Example 2, and itscomponents were examined. As a result, this fraction B was composed of99.9% by mass of methyl alcohol and 0.1% by mass of water, and it wasnot confirmed that methyl acrylate was included.

Example 11

A transesterification reaction was carried out in the same manner as inExample 1 except that 615.2 g (7.15 moles) of methyl acrylate, 892.1 g(5.50 moles) of 3-ethyl-3-oxetanylmethyl alcohol and 5.1 g of dioctyltinoxide were used in Example 1. After the termination of the reaction, theamount of methyl acrylate contained in the reaction mixture which wasobtained by the transesterification reaction was 123 g. Aftercyclohexane was added to the flask, and 122 g of unreacted methylacrylate was collected, the content of methyl acrylate in the reactionmixture included in the flask was examined. As a result, the content ofmethyl acrylate was at most 0.1% by mass.

Next, the lower layer of the decanter was distilled in the same manneras in Example 1. As a result, a fraction A was composed of 62.3% by massof methyl alcohol, 32.1% by mass of methyl acrylate, 5.5% by mass ofcyclohexane and 0.1% by mass of water. This fraction A could be usedwhen a transesterification reaction of methyl acrylate and3-ethyl-3-oxetanylmethyl alcohol was carried out. Subsequently, afraction B was collected in the same manner as in Example 2, and itscomponents were examined. As a result, this fraction B was composed of99.9% by mass of methyl alcohol and 0.1% by mass of water, and it wasnot confirmed that methyl acrylate was included.

Example 12

A system for producing a (meth)acrylate shown in FIG. 2 was used. As areactor A having a distillation column, a 2-liter four-necked flaskhaving a 20-stage Oldershaw distillation column (number of theoreticalstages: 15) equipped with a condensing apparatus at its top and having aside tube, and an air intake tube was used. The flask was charged with694 g (8.06 moles) of methyl acrylate, 552 g (6.20 moles) ofN,N-dimethylaminoethanol, 1.76 g of phenothiazine, 22.1 g of dibutyltinoxide and 100 g of cyclohexane. A transesterification reaction wascarried out while blowing air into the flask from the air intake tube ata flow rate of 20 mL/min. More specifically, vapor which was taken outfrom the top of the distillation column was condensed in the condensingapparatus, a part of the resulting condensate was refluxed to the top ofthe distillation column, and the remaining condensate was removed fromthe flask. The temperature at the top of the distillation column wascontrolled to an azeotropic temperature of methyl alcohol andcyclohexane of 54° C. to 56° C. by adjusting the amount of thecondensate removed.

The condensate which was removed from the top of the distillation columnin an amount of 700 g was mixed with 200 g of water at a temperature of20° C., and the resulting mixed solution was fed to a decanter. Thismixed solution was separated into two layers of an upper layer and alower layer. Since methyl alcohol contained in the condensate wasextracted with water, the methyl alcohol was contained in the lowerlayer, and the cyclohexane included in the condensate was contained inthe upper layer.

The amount of the above-mentioned lower layer was 410 g, and the lowerlayer contained 48.5% by mass of methyl alcohol, 0.6% by mass ofcyclohexane, 3.4% by mass of methyl acrylate and 47.5% by mass of water.

On the other hand, the above-mentioned upper layer was effectively usedby feeding the upper layer to the distillation column at the middlestage of the distillation column where a 10th stage was provided fromthe bottom of the distillation column.

A transesterification reaction of methyl acrylate andN,N-dimethylaminoethanol was carried out while properly addingcyclohexane to the flask so that the reaction temperature was 85° C. to102° C. When 4 hours passed from the initiation of the reaction, thetransesterification reaction was terminated. After the termination ofthe reaction, the amount of methyl acrylate contained in the reactionmixture which was obtained by the above-mentioned transesterificationreaction was 160 g.

After the termination of the reaction, a reaction mixture obtained bythe above-mentioned transesterification reaction was further heated in areflux ratio of 10 to 15, vapor was taken out from the top of thedistillation column, and the vapor was condensed to collect acondensate. At that time, cyclohexane was added to the flask so that thetemperature of the reaction mixture included in the flask was maintainedto 85° C. to 100° C. While taking out the condensate from the top of thedistillation column, the temperature at the top of the distillationcolumn gradually increased. The distillation was continued until thetemperature at the top of the distillation column attained to a boilingpoint of cyclohexane of 80° C.

As a result, the content of methyl acrylate in the reaction mixtureincluded in the flask was at most 0.1% by mass. In addition, thecondensate was taken out from the top of the distillation column. Theamount of the collected condensate was 490 g. This condensate contained5 g of methanol, 145 g of methyl acrylate and 340 g of cyclohexane. Thiscondensate contained most of the methyl acrylate used in an excessiveamount. This collected condensate could be used when atransesterification reaction of methyl acrylate andN,N-dimethylaminoethanol was carried out. From this fact, it wasconfirmed that loss of methyl acrylate could be prevented by using theabove-mentioned condensate when a transesterification reaction of methylacrylate and N, N-dimethylaminoethanol was carried out.

As a result of the preparation of N,N-dimethylaminoethyl acrylate asdescribed above, the yield of N,N-dimethylaminoethyl acrylate was 852 g(yield on the basis of N,N-dimethylaminoethanol: 96% by mass; yield onthe basis of the charged amount of methyl acrylate: 73.8% by mass; yieldin the case where methyl acrylate which was collected by the azeotropewith cyclohexane was reused: 93.3% by mass).

From the above results, when the reactor A is used, it can be seen thatthe condensate can be effectively used by mixing the condensate whichwas removed from the top of the distillation column with water,separating the resulting mixed solution into two layers, and supplyingthe upper layer obtained to the distillation column, that the condensatecan be effectively used in a new transesterification reaction by furtherheating the reaction mixture which was obtained by thetransesterification reaction, and collecting the condensate from the topof the distillation column, and that an objective N,N-dimethylaminoethylacrylate can be prepared in a high yield.

Next, as a distillation apparatus B, a 1-liter four-necked flask havinga 20-stage Oldershaw distillation column equipped with a condensingapparatus at its top and having a side tube, and an air intake tube wasused. The Oldershaw type distillation column was continuously chargedwith the lower layer obtained in the above at a flow rate of 200 g/hfrom the middle stage (10th stage) of the distillation column.

A distillation was carried out while refluxing to the top of thedistillation column in a reflux ratio of 50, and a part of thecondensate obtained in the condensing apparatus was taken out from thecondensing apparatus at a flow rate of 22 g/h. As a result, thecondensate was composed of 46.3% by mass of methyl alcohol, 32.7% bymass of methyl acrylate and 21.0% by mass of cyclohexane. Thiscondensate was effectively used by returning to the reactor A.

On the other hand, the components of the liquid taken out from the lowerstage of the distillation apparatus B were examined. As a result, theliquid was composed of 57.8% by mass of water and 42.2% by mass ofmethyl alcohol.

Next, as a distillation apparatus C, a 1-liter four-necked flask havinga 20-stage Oldershaw distillation column equipped with a condensingapparatus at its top and having a side tube, and an air intake tube wasused. The Oldershaw distillation column was continuously charged withthe liquid obtained in the above at a flow rate of 184 g/h from themiddle stage (10th stage) of the distillation column.

A distillation was carried out while refluxing to the top of thedistillation column in a reflux ratio of 1.4, and a part of thecondensate obtained in the condensing apparatus was taken out from thecondensing apparatus at a flow rate of 76 g/h. As a result, thecondensate was composed of 99.5% by mass of methyl alcohol and 0.5% bymass of water. Since this condensate had a high content of methylalcohol, the condensate could be suitably used as a fuel and in thesynthesis of an organic compound.

On the other hand, the components of the liquid taken out from the lowerstage of the distillation apparatus C were examined. As a result, theliquid was composed of 100% by mass of water. This water could besuitably used in the separation apparatus of the reactor A.

From the above results, it can be seen that according to Example 12, notonly (meth)acrylate which is used as an unreacted raw material and asolvent but also a by-product alcohol and by-product water can beeffectively used.

Comparative Example 1

The same reactor A as used in Example 1 was used. The flask was chargedwith 694 g (8.06 moles) of methyl acrylate, 552 g (6.20 moles) ofN,N-dimethylaminoethanol, 1.76 g of phenothiazine, 22.1 g of dibutyltinoxide and 100 g of isohexane.

Next, a transesterification reaction was carried out at a reactiontemperature of 76° C. to 93° C. while blowing air into the flask at aflow rate of 20 mL/min. More specifically, vapor which was taken outfrom the top of the distillation column of the reactor was condensed. Apart of the resulting condensate was refluxed to the upper part of thedistillation column, and the remaining condensate was removed from thereactor. The temperature at the top of the distillation column wascontrolled to an azeotropic temperature of methyl alcohol and isohexaneof 45° C. to 56° C. by adjusting the amount of the condensate removedfrom the flask.

The condensate removed from the reactor in an amount of 950 g was mixedwith 200 g of water at a temperature of 20° C., and the resulting mixedsolution was introduced to a decanter to separate the mixed solutioninto two layers. The lower layer of the two layers contained methylalcohol which had been included in the condensate. On the other hand,the upper layer contained isohexane. The upper layer was fed to the 10thstage of the distillation column from the bottom, which was a middlestage of the distillation column.

The transesterification reaction of methyl acrylate andN,N-dimethylaminoethanol was carried out for 13 hours, and the reactionof methyl acrylate and N, N-dimethylaminoethanol was terminated.

At the time of termination of the reaction, the amount of methylacrylate remaining in the reactor was 160 g.

Next, a distillation was carried out in a reflux ratio of 10 to 15 whileadding isohexane to the flask so that the temperature of the reactionmixture included in the flask was 80° C. to 90° C., and a condensate wastaken out from the top of the distillation column. When the condensatewas taken out from the top of the distillation column, the temperatureat the top of the distillation column immediately attained to a boilingpoint of isohexane of 62° C. The amount of the condensate taken out fromthe top of the distillation column was 300 g.

As a result, the amount of methyl acrylate remaining in the reactor was10.8% by mass. In addition, 300 g of the condensate taken out from thetop of the distillation column contained 5 g of methanol, 5 g of methylacrylate and 290 g of isohexane. From this fact, it was confirmed thatthe above-mentioned condensate contained little methyl acrylate whichwas used as a raw material, and that almost of the methyl acrylateremained in the reactor.

From the above results, the amount of methyl acrylate remaining in thereactor at the time of termination of the reaction was 160 g. Inaddition, after the termination of the reaction, methyl acrylate did notform an azeotropic mixture together with isohexane, and only 5 g of themethyl acrylate could be collected.

Comparative Example 2

A 2-liter four-necked flask having a 20-stage Oldershaw distillationcolumn (number of theoretical stages: 15) equipped with a condensingapparatus at its top and having a side tube, and an air intake tube wasused as a reactor. The flask of the reactor was charged with 694 g (8.06moles) of methyl acrylate, 552 g (6.20 moles) ofN,N-dimethylaminoethanol, 1.76 g of phenothiazine, 22.1 g of dibutyltinoxide and 100 g of cyclohexane. A transesterification reaction wascarried out while blowing air into the flask from the air intake tube ata flow rate of 20 mL/min.

More specifically, vapor which was taken out from the top of thedistillation column of the reactor was condensed. A part of theresulting condensate was refluxed to the top of the distillation column,and the remaining condensate was removed from the reactor. Thetemperature at the top of the distillation column was controlled to anazeotropic temperature of methyl alcohol and cyclohexane of 54° C. to56° C. by adjusting the amount of the condensate removed from the flask.

The condensate which was removed from the top of the distillation columnof the reactor in an amount of 700 g was mixed with 200 g of water at atemperature of 20° C., and the resulting mixed solution was introducedto a decanter. This mixed solution was separated into two layers of anupper layer and a lower layer. Since methyl alcohol contained in thecondensate was extracted with water, the methyl alcohol was contained inthe lower layer, and the cyclohexane included in the condensate wascontained in the upper layer. The amount of the lower layer was 410 g,and the lower layer contained 47.0% by mass (193 g) of methyl alcohol,0.5% by mass (2 g) of cyclohexane, 3.6% by mass (15 g) of methylacrylate and 48.9% by mass (200 g) of water.

A transesterification reaction of methyl acrylate andN,N-dimethylaminoethanol was carried out while properly addingcyclohexane to the flask so that the reaction temperature was 85° C. to102° C. When 4 hours passed from the initiation of the reaction, thetransesterification reaction was terminated.

As a result, the yield of N,N-dimethylaminoethyl acrylate was 96.0% bymass, and the yield on the basis of methyl acrylate was 73.8% by mass.In addition, a water layer obtained by extracting methanol from thecondensate contained 48.0% by mass of methanol, 0.1% by mass of n-hexaneand 3.6% by mass of methyl acrylate, and the amount of methyl acrylateremaining in the reactor was 160 g.

Therefore, according to the method employed in Comparative Example 2, itcan be seen that methyl acrylate remains in the reactor in a largeamount.

From the above results, according to each of the working examples of thepresent invention, it can be seen that (meth)acrylate which is used as araw material remaining after the transesterification reaction of(meth)acrylate which is used as a raw material and an alcohol can beefficiently collected, and that the collected (meth)acrylate which isused as a raw material can be reused when a transesterification reactionof a (meth)acrylate which is used as a raw material and an alcohol iscarried out.

EXPLANATION OF REFERENTIAL NUMBERS

-   -   1 reactor A    -   2 distillation column    -   3 distillation apparatus B    -   4 distillation column    -   5 a to 5 f pipe    -   6 condensing apparatus    -   7 switching apparatus    -   8 liquid separation apparatus    -   9 condensing apparatus    -   10 a to 10 e pipe    -   11 switching apparatus    -   12 collecting unit    -   13 distillation column    -   14 distillation apparatus C    -   15 heating apparatus    -   16 pipe    -   17 heating apparatus    -   18 a to 18 e pipe    -   19 condensing apparatus    -   20 switching apparatus    -   21 collecting unit

1. A system for producing a (meth)acrylate used in producing a(meth)acrylate by transesterification, comprising a reactor A having adistillation column and a distillation apparatus B having a distillationcolumn, wherein an upper part of the distillation column of the reactorA is connected with a condensing apparatus through a pipe; thecondensing apparatus is connected with the upper part of thedistillation column through a switching apparatus with a pipe forrefluxing a part of a condensate obtained in the condensing apparatus tothe upper part of the distillation column; and the condensing apparatusis connected with a liquid separation apparatus through a switchingapparatus with a pipe for feeding the condensate remaining in thecondensing apparatus to the liquid separation apparatus; an upper partof the liquid separation apparatus is connected with the distillationcolumn through a pipe for refluxing an upper layer of the condensateseparated by the liquid separation apparatus to the distillation column;and a lower part of the liquid separation apparatus is connected withthe distillation apparatus B through a pipe for feeding a lower layer ofthe condensate separated by the liquid separation apparatus to thedistillation apparatus B; an upper part of the distillation column ofthe distillation apparatus B is connected with a condensing apparatusthrough a pipe; the condensing apparatus is connected with the upperpart of the distillation column through a switching apparatus with apipe for refluxing a part of a condensate obtained in the condensingapparatus to the upper part of the distillation column; and thecondensing apparatus is connected with a collecting unit for collectingthe condensate remaining in the condensing apparatus through a switchingapparatus with a pipe for feeding the remaining condensate to thecollecting unit; and a lower part of the distillation apparatus B isconnected with a pipe between the switching apparatus and the condensingapparatus in the reactor A through a pipe for refluxing a residueexisting in the distillation apparatus B to the distillation column ofthe reactor A.
 2. A system for producing a (meth)acrylate used inproducing a (meth)acrylate by transesterification, comprising a reactorA having a distillation column, a distillation apparatus B having adistillation column and a distillation apparatus C having a distillationcolumn, wherein an upper part of the distillation column of the reactorA is connected with a condensing apparatus through a pipe; thecondensing apparatus is connected with the upper part of thedistillation column through a switching apparatus with a pipe forrefluxing a part of a condensate obtained in the condensing apparatus tothe upper part of the distillation column; and the condensing apparatusis connected with a liquid separation apparatus through the switchingapparatus with a pipe for feeding the condensate remaining in thecondensing apparatus to the liquid separation apparatus; an upper partof the liquid separation apparatus is connected with the distillationcolumn through a pipe for refluxing an upper layer of the condensateseparated by the liquid separation apparatus to the distillation column;and a lower part of the liquid separation apparatus is connected withthe distillation apparatus B through a pipe for feeding a lower layer ofthe condensate separated by the liquid separation apparatus to thedistillation apparatus B; an upper part of the distillation column ofthe distillation apparatus B is connected with a condensing apparatusthrough a pipe; the condensing apparatus is connected with the upperpart of the distillation column through a switching apparatus with apipe for refluxing a part of a condensate obtained in the condensingapparatus to the upper part of the distillation column; and thecondensing apparatus is connected with a collecting unit for collectingthe condensate remaining in the condensing apparatus through a switchingapparatus with a pipe for feeding the remaining condensate to thecollecting unit; a lower part of the distillation apparatus B isconnected with the distillation apparatus C through a pipe for feeding aresidue existing in the distillation apparatus B to the distillationcolumn of the distillation apparatus C; an upper part of thedistillation apparatus C is connected with a condensing apparatusthrough a pipe; the condensing apparatus is connected with the upperpart of the distillation column through a switching apparatus with apipe for refluxing a part of a condensate obtained in the condensingapparatus to the upper part of the distillation column; and thecondensing apparatus is connected with a collecting unit for collectingthe condensate remaining in the condensing apparatus through a pipe forfeeding the condensate remaining in the condensing apparatus to thecollecting unit; and a lower part of the distillation apparatus C isconnected with a pipe between the switching apparatus and the condensingapparatus in the reactor A through a pipe for feeding a residue existingin the distillation apparatus C to the distillation column of thereactor A.